composition of functions??

[wendywoo]

f(x)= cos pi x and g(x)= sin pi x

the value of f[g(3/2)] is.......i plugged g(x) into f(x). and i got cos pi sin pi x. but the answer is -1. how can i get it to -1??

 

[burakaltr]

f(x)= cos pi x and g(x)= sin pi x

the value of f[g(3/2)] is.......i plugged g(x) into f(x). and i got cos pi sin pi x. but the answer is -1. how can i get it to -1??

g(3/2)=sin 1.5 pi = sin 270 degrees = -1

f(-1)=cos-pi= -1

 

[wendywoo]

okay i sort of get it now. does anyone know how to find zeros in trigonometric functions? for example. are there any zeros in sin2x? if yes how do you find them?

 

[mmm4444bot]

are there any zeros in sin2x?

This question indicates that you're missing something basic.

Graph the function y = sin(2x) and look at the curve.

If the graph does not enable you to answer your question quoted above, then you should tell us exactly why.

 

[wendywoo]

i graphed it on my calculator. so a zero occurs every time the line crosses the x axis yes?