Question #0e194

1 Answer
Apr 7, 2017

First, change all trigonometric functions to sin(x) and cos(x) by using the identities csc(x)=1/sin(x) and cot(x)=1/tan(x)=1/(sin(x)/cos(x))=cos(x)/sin(x).

This results in sin(x)/(1-cos(x))=1/sin(x)+cos/sin(x). Add the two fractions on the right-hand side: sin(x)/(1-cos(x))=(1+cos(x))/sin(x).

Now, multiply both sides by sin(x)(1-cos(x)) to eliminate the fractions. The equation becomes sin^2(x)=(1+cos(x))(1-cos(x)). Expand the right-hand side by using the identity (a+b)(a-b)=a^2-b^2.

This results in sin^2(x)=1-cos^2(x). Add cos^2(x) to both sides to get sin^2(x)+cos^2(x)=1, which is one of the trigonometry identites.