.
Find all solutions in the interval [0,360)
cos^2(theta)+8cos(theta)+5=0
~~~~~~~~~~~~~~~~
= 0.
Introduce new variable x = . Then your equation takes the form
= 0.
Apply the quadratic formula to solve for x:
= = = .
1) = =~ -0.68.
= ====> = and = .
2) = < -1.
There is NO satisfying = .
Answer. The original equation has two solutions = and = .
Solved.
If you want to see more solved problems/samples on trigonometric equations, look into the lessons
- Solving simple problems on trigonometric equations
- Solving typical problems on trigonometric equations
- Solving more complicated problems on trigonometric equations
- Solving advanced problems on trigonometric equations
- OVERVIEW of lessons on calculating trig functions and solving trig equations
in this site.
Also, you have this free of charge online textbook in ALGEBRA-II in this site
- ALGEBRA-II - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Trigonometry: Solved problems".