Question

show that if f(x)=sinx then f'(x)=cos x
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Answer 1

Answer:

TRIGONOMETRIC FUNCTIONS. THE DERIVATIVE of sin x is cos x. To prove that, we will use the following identity: sin A − sin B = 2 cos ½(A + B) sin ½(A − B). Since the cosine is the x-coordinate of the points on the unit circle, you see that the two points have the same cosine, and opposite sine. The cosine is an even function, which means exactly that cos(-x) = cos

Answer 2

Step-by-step explanation:

by first principle rule

f'(x) = limx--o [f(x+h)-f(x)]/h