Posted by Patrick on Wednesday, April 22, 2009 at 10:54am.
Use the sum or difference identity to find the exact value of sin255 degrees.
My answer: (sqrt(2) sqrt(6)) / (4)
Find the value of tan (alphabeta), if cos alpha= 3/5, sin beta= 5/13, 90<alpha<180, and 90<beta<180.
My answer: 33/56
Which expression is equivalent to cos(pitheta)?
Is it cos theta?
Which expression is not equivalent to cos 2theta?
a. cos^2 theta sin^2 theta
b. 2cos^2 theta  1
c. 1  2sin^2 theta
d. 2sin theta cos theta
I would pick D.

Pre Calc.  Reiny, Wednesday, April 22, 2009 at 11:23am
correct on all counts, good job
For questions on finding "exact" values for certain trig ratios, a quick way to check your result is to simply evaluate your answer with a calculator, then compare it to the calculator result for the initial trig ratio
e.g. for yours I found (sqrt(2) sqrt(6)) / (4) to be .9659258
and sin 255 to be .9659258 , not bad eh?
Answer This Question
Related Questions
 trig  evaluate the following in exact form, where the angeles alpha and beta ...
 Math  Given that sin alpha=4/sqrt65, pi/2<alpha<pi, and cos beta=3/...
 Math/Calculus  Solve the initialvalue problem. Am I using the wrong value for ...
 Math ( Polynomial )  This time three questions  1. If (x^2  1 ) is a factor ...
 Math ( Polynomial )  This time three questions  1. If (x^2  1 ) is a factor ...
 Calculus  The question will first read in English followed by a reading in ...
 Math  If alpha and beta are the zeros of the polynomial ax^2 + bx + c then ...
 Trig.  I have answers for these problems, but I wanted to check if I had them ...
 physics  Two radar stations A and B, are separated by horizontal distance of (a...
 maths  if alpha and beta are the zeros of the polynomial 2x^24x+5 then find ...
More Related Questions