# trig question

#### besito2001

I need help if any one has suggestions

y=sin (3x+ pi/2)

#### harish21

I need help if any one has suggestions

y=sin (3x+ pi/2)
$$\displaystyle sin(A+B) = sinA.cosB + cosA.sinB$$
so if you substitute $$\displaystyle A=3x$$ and $$\displaystyle B= \frac{\pi}{2}$$,
you have $$\displaystyle y=cos(3x)$$