How do you express cot^3theta-cos^2theta-tan^2theta in terms of non-exponential trigonometric functions?

2 Answers
Jun 9, 2018

(cos^5(x)-sin^5(x)-cos^4(x)sin^3(x))/(sin^3(x)*cos^2(x))

Explanation:

We write
1/tan^3(x)-tan^2(x)-cos^2(x)

(1-tan^5(x))/tan^3(x)-cos^2(x)

(1-tan^5(x)-tan^3(x)*cos^2(x))/tan^3(x)

(1-tan^5(x)-sin^2(x)/cos(x))/tan^3(x)

(cos(x)-cos(x)tan^5(x)-sin^3(x))/(cos(x)tan^3(x))

(cos^5(x)-sin^5(x)-cos^4(x)sin^3(x))/(sin^3(x)cos^2(x))

Aug 10, 2018

( cos 3theta + 3 sin theta }/( 3 sin theta - sin 3theta )
- 1/2 ( 1 + cos 2theta ) -( 1 - cos 2theta )/( 1 + cos 2theta )

Explanation:

Use

cos 3A = 4 cos^3A - 3 cos A and sin 3A = 3 sin A - 4 sin^3A.

cot^3theta - cos^2theta - tan^2theta

= cos^3theta/sin^3theta - cos^2theta - sin^2theta/cos^2theta

= ( cos 3theta + 3 sin theta }/( 3 sin theta - sin 3theta )

- 1/2 ( 1 + cos 2theta ) -( 1 - cos 2theta )/( 1 + cos 2theta )