Verify the identity.

cos (x+(pi/2)) = -sin x

Question

Verify the identity. 

cos (x+(pi/2)) = -sin x

campbell_st · Answer

well use the difference of 2 angles 

cos(A + B) = cos(A)cos(B) - sin(A)sin(B)

thats 1 method

anonymous · Answer

cos (x+(pi/2)= cos x

campbell_st · Answer

oops sum not difference

anonymous · Answer

cos=-sinx thats basically what im trying to figure out now

campbell_st · Answer

well if you make the subsitution you get

$$\cos(x + \frac{\pi}{2}) = \cos(x)\cos(\frac{\pi}{2}) - \sin(x) \sin(\frac{\pi}{2})$$

whats the value of cos(pi/2)..?

whats the value of sin(pi/2)

substitute them and seem what happens

anonymous · Answer

wait i did the identities wrong

anonymous · Answer

this is so confusing :(

campbell_st · Answer

an anternative is to graph the curve cos(x)  

then graph cos(x + pi/2)   pi/2 causes a phase shift of pi/2 to the left.... the resulting cruve... is -sin(x)

anonymous · Answer

ok