







sin 2x  sin x = 0 
20160424 

lilly pose la question : sin 2x  sin x = 0 0 Penny Nom lui répond. 





Solve for theta 
20140425 

ALASTAIR pose la question : Hi, The question asks Solve for 'theta' cos2theta=sintheta x costheta.
Substituting for cos2th either 12sin^2th or 2cos^2th does not give an equation in either sine or cosine alone how do I solve this please? Penny Nom lui répond. 





siin (A) and sin (A/2) 
20130509 

shanaia pose la question : given that sin A=4/5 and A is obtuse.find sin (A/2) Penny Nom lui répond. 





Tan(x+pi)tan(pix)=2tan(x). 
20110109 

Steven pose la question : Verify the identity:
Tan(x+pi)tan(pix)=2tan(x) Penny Nom lui répond. 





A trig equation 
20100428 

Steve pose la question : 2cos^2(X)2sin^2(x)+1=0 Harley Weston lui répond. 





A cube with twice the volume 
20100411 

Woojin pose la question : From a given cube create another cube with twice the volume.
the cube: 5cm each. Tyler Wood lui répond. 





Integration of cos (x^2+y^2) dx dy 
20100212 

anna pose la question : How do you evaluate the integration of integration of cos (x^2+y^2) dx dy? Tyler Wood lui répond. 





Trigonometry and picture hanging 
20100113 

george pose la question : The top of a picture 1m high 0.8m from the ceiling. At a point on the ceiling directly in front of the picture, we wish to install a light so that the angle subtended by the picture equals to the angle of depression of the top of the picture. How far out from the wall should the light be installed? Penny Nom lui répond. 





A double discount 
20081006 

Joanna pose la question : An instrument store gives a 10% discount to all students off the original cost of an instrument. During a back to school sale an additional 15% is taken off the discounted price. Julie, a student at the local high school, purchases a flute for $306. How much did it originally cost? Penny Nom lui répond. 





TRIG IDENTITIES 
20080817 

VINCE pose la question : HOW DO YOU SIMPLIFY THE FOLLOWING:
2sin3(theta)cos3(theta)?
Regards Harley Weston lui répond. 





Graphing Using Double Angle Identities 
20080716 

Hodan pose la question : the Question is:
Describe how you could use your knowledge of Double angle formulas to sketch the graph of each function. Include a sketch with your description.A) F(x)=sin x cos x
B)F(x)=2 cos(squared)x
C) F(x)= tan(x) (divided) by 1tan(squared) x Janice Cotcher lui répond. 





A number that ends with 2 
20080623 

Jim pose la question : A number ends in 2. If you were to place that digit at the beginning of the
number, the resulting number will be twice the original. Find the smallest
such number. Stephen La Rocque lui répond. 





sin(2x)/sin(3x) 
20080619 

matt pose la question : how does sin2x break down (not with identities) and how would sin3x be created. My
prob. is sin 2x/ sin 3x and I want to know how the double(or triple angle) would break
down. I want to be able to cancel out sins. Thanks! Harley Weston lui répond. 





Double one penny for 30 days 
20080611 

kerwin pose la question : one penny doubled for 30 days what is the answer? Penny Nom lui répond. 





Double the the dimensions of a rectangle 
20080522 

Destiny pose la question : Double the the dimensions of a rectangle that is 3 by 4 in. What is the area? Penny Nom lui répond. 





The probability of rolling double sixes twice in a row 
20070710 

Matt pose la question : what is the probability of rolling double sixes twice in a row? Stephen La Rocque lui répond. 





Take $.01 and double it every day for 30 days. 
20070126 

Pat pose la question : Take $.01 and double it every day for 30 days. How many dollars would you have? Stephen La Rocque lui répond. 





sin x + sin 2x + sin 3x + sin 4x = 0 
20050510 

Elia pose la question : I tried many times, but can't get to solve the following question:
sin x + sin 2x + sin 3x + sin 4x = 0 Chris Fisher lui répond. 





cos(2x) = sin(3x) 
20050414 

A student pose la question : Show that if x= 18 degrees, then cos2x =sin 3x. HENCE find the exact value of sin 18 degrees, and prove that cos 36  sin 18 =1/2. Andrei Volodin, Claude Tardif and Penny Nom lui répond. 





Doubling time 
20050312 

Nick pose la question : Looking for the equation to how many years it will take to double the population given the growth rate is 7%. Penny Nom lui répond. 





sin(3A) 
20041020 

A student pose la question : Express sin3A in terms of sinA and cosA. Penny Nom lui répond. 





Wages for one month 
20040920 

Janet pose la question : if offered $10,000 or 1 cent on the first day and then doubled daily for one month which would you take ? Harley Weston lui répond. 





Some trig expressions 
20040523 

A student pose la question : Prove:
sin A + sin B = 2sin(A+B/2)cos(AB/2)
cos A  cos B = 2sin(A+B/2)sin(AB/2)
cos A + cos B = 2cos(A+B/2)cos(AB/2)
sin A  sin B = 2cos(A+B/2)sin(A+B/2) Penny Nom lui répond. 





33 3/4 doubled 
20040522 

A tailor pose la question : need to know how to add 33 3/4 doubled. How do I come up with the solution? I need to know for measuring garments. Usually I measure on the half meaning on the front of the garment and then double it with the measuring tape but I always get stuck when I need to measure 3/4 such as 66 3/4 doubled and etc. Can you help me figure this out easily. Penny Nom lui répond. 





$1/week for week 1 and then double each week 
20030528 

A student pose la question : I AM DOING A PROJECT FOR MATH I AM TRYING TO CREATE A SEQUENCE BASED ON: MAKING A SALARY OF $1/WK FOR THE FIRST WEEK WITH IT DOUBLING EVERY WEEK FOR 52 WEEKS, SO MY SEQUENCE LOOKS LIKE THIS: 1,2,4,8,16,32,64,128,256,512,1024 ETC. THERE WOULD BE 52#'s TOTAL IN MY SEQUENCE.I BELIEVE IT IS CALLED A FINITE SEQUENCE. MY QUESTION IS HOW DO I CREATE A FORMULA/RULE FOR THIS PARTICULAR SEQUENCE? MY GOAL BEING TO FIND THE 52nd TERM IN THE SEQUENCE. Penny Nom lui répond. 





Write sin(3x) in terms of sin(x) 
20030505 

A student pose la question : Write sin 2x in terms of sin x Penny Nom lui répond. 





Doubling the size of an object 
20030401 

Dave pose la question : If I have a known surface area and volume of an unknown object and I want to double the size of the object, how do I find the new area and volume? Walter Whiteley lui répond. 





Conics 
20020529 

Brooke pose la question : Which conic cannot be generated by an intersection of a plane and a double napped cone? Chris Fisher lui répond. 





The median with ties 
20020227 

Marcel pose la question : What, exactly, is the proper way to determine the median of a set of numbers when doubles or triples of a number are part of that set? Do the doubles count as two and the triples three, or does each count only as one toward determining the median. Harley Wston lui répond. 





sin 2x = cos 3x 
20020225 

Allan pose la question : solve: sin 2x = cos 3x Primary question: how do you handle the cos 3x? Paul Betts and Chris Fisher lui répond. 





Double square roots 
20020217 

Ali pose la question : i have a question about how to do double square roots with variables and powers. example : v/"" v/"" 81y^{8} Harley Weston lui répond. 





My salary is doubled everyday for 30 days 
20020117 

Kanishk pose la question : I recieve 1 penny the 1st day, 2 pennies the 2nd day, and my salary is doubled everyday for 30 days. How much money will I have by the end of the 30 day time period? (Is there a way of solving this problem without a chart?) Penny Nom lui répond. 





Double bar graphs 
20010909 

Leslie pose la question : My daughter has a homework problem in which she is graphing data from two frequency tables onto a double bar graph. The graph shows how many students worked in a program in two different years, grouped by age. In the first age group, one of the years has no students working, while there were students in that age group in the other year. Penny Nom lui répond. 





7x6 by doubling 
20010123 

A student pose la question : Can you think of a way to use doubling to multiply 6x7? Allen Herman lui répond. 





Triple angle formula 
20000223 

Sara pose la question : Can one derive a triple angle formula for sine and cosine? If so, how? Chris Fisher lui répond. 





Tennis doubles 
20000204 

Brittany Allinson pose la question : Cheri, Beth and Jacinta are daughters of Mr. Sullivan, Mr. Marchand, and Mr. Benoit. Four of these people are playing tennis doubles. Mr. Benoit's daughter and Mr. Sullivan are partners. Cheri's father and Mr. Marchand's daughter are also partners. There aren't any father/daughter combinations. Who is Cheri's father? Penny Nom lui répond. 





A double negative 
19990901 

Dennis pose la question : If b = 2 what does b = ? As in (a + 8.5)  [(b) + c] a = 1.5, c = 1.7 Penny Nom lui répond. 





A Trigonometry Question 
19990828 

Diane Simms pose la question : My question is can the following be factored. I am a teacher who needs the factors to this right away. 2 Sin^{2}X + 2 SinX CosX  1= 0 Harley Weston lui répond. 





Sin 4A 
19990622 

Ryan Cochrane pose la question : If sinA = 4/5, and A is a first quadrant angle, find sin4A Harley Weston lui répond. 

