Posted by Kevin on Sunday, November 13, 2011 at 4:51pm.
I have these sum and product property problems and I just want to make sure my work is right.
Write equations expressing
1. cos 37degrees cos99degrees as a sum
Answer: sin136+(62)
2. sin4+sin7 as a product
Answer: 2sin5.5 sin1.5
3. cos 8x  cos 2x as a product
Answer 2sin5x sin3x
4. cos5x sin9x as a sum
Answer sin14x  (4)
Idk...I just don't feel as confident about these

Trig  Steve, Monday, November 14, 2011 at 10:35am
recall that
cosa * cosb = 1/2[cos(a+b) + cos(ab)]
cos37 cos99 = 1/2(cos126 + cos(62))
= 1/2 (cos126 + cos62)
since cos(a) = cos(a)
So, your answers have the right number sin them, but you need to tidy them up to conform to the identities.
Answer This Question
Related Questions
 trig  I have these sum and product property problems and I just want to make ...
 TRIG!  Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
 math  Find the two numbers that multiply to the product number and add to the ...
 Math  Use the producttosum formulas to write the product as a sum or ...
 Math  What is 2 + 2? = 4 What is 2 * 2? = 4 So, the sum and the product of ...
 PreCal (Trig) Help?  The following relationship is known to be true for two ...
 Algebra 2  Q: Write a quadratic equation with integral coefficients whose roots...
 trig  Establish the trigonometric identity (Hint: Use sum to product) cos(5x)+...
 Calculus 12th grade (double check my work please)  1.)Find dy/dx when y= Ln (...
 Math  1. use the suitable producttosum formula to rewrite the following ...
More Related Questions