Whether cos^2(theta)+cos(theta)=0 or cos^2(theta)=cos(theta)=0 is the intended question, the solution cos(theta)=0 applies, and theta=(2n+1)π/2 where n is an integer. In terms of degrees theta=90+180n=90(2n+1).

There is an additional solution for cos^2(theta)+cos(theta)=0, because cos(theta)(cos(theta)+1)=0 also has the solution cos(theta)=-1, and theta=π(2n+1) where n is an integer, or 180(2n+1).

cos theta(cos theta+1)=0

cos theta =0 or cos theta =-1

**Free Trigonometry Help**

- All categories
- Pre-Algebra Answers 12,306
- Algebra 1 Answers 25,235
- Algebra 2 Answers 10,430
- Geometry Answers 5,157
- Trigonometry Answers 2,637
- Calculus Answers 5,997
- Statistics Answers 3,016
- Word Problem Answers 10,085
- Other Math Topics 6,622

81,485 questions

85,664 answers

2,174 comments

69,138 users