Arturo O. answered • 07/20/17
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Use the trigonometric identity
sin(2x) = 2 cosx sinx
Then
2sin35° cos35° = sin[2(35°)] = sin70°
Kenneth S.
Student, Arturo has used the Pattern Recognition practice. It's something you should learn to do.
As you proceed to Calculus, you will find there that simplifying trigonometric expressions is VERY VALUABLE. So LEARN the key Trigonometric formula for double angles, half angles, and identities--they will be the difference between constantly struggling in Calculus, or the alternative, which is slick simplifications and substitutions, and success.
By LEARN, I mean both MEMORIZE and UNDERSTAND.
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07/20/17
Arturo O.
Expanding a little on what Kenneth said:
If you go into engineering or physics, you will work with all kinds of wave equations whose solutions involve products of trigonometric functions. Knowing the identities for sin(x ± y), cos(x ± y), sin(2x), cos(2x), and several others will let you simplify the expressions greatly, making it much easier to take derivatives, integrate, etc.
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07/20/17
Muhaman H.
07/20/17