Posted by Greg on Tuesday, January 14, 2014 at 10:55pm.
Mark any solutions to the equation 2cos2x - 1 = 0. The answer can be more than one. Thank you
- TRIG help quickly please - Reiny, Tuesday, January 14, 2014 at 11:22pm
2 cos (2x) - 1 = 0
cos (2x) = 1/2
2x = π/3 or 2x = 2π-π/3 or 5π/3
x = π/6 or x = 5π/6
none of the given answers apply
I will assume you meant
2 cos^2 x - 1 = 0
2cos^2 x -1 = cos (2x)
so cos(2x) = 0
2x = π/2 or 2x = 3π/2
x = π/4 or x = 3π/4
I see one of those answers. 3π/4
looking at the others, note that -7π/4 is coterminal with π/4
so it would be a solution as well
Answer this Question
- Math, please help - Which of the following are trigonometric identities? (Can be...
- Trig - find all solutions to the equation √3 csc(2theta)=-2 Would the ...
- Math integrals - What is the indefinite integral of ∫ [sin (π/x)]/ x^...
- Trig Help! - Question: Trying to find cos π/12, if cos π/6 = square ...
- Calculus - How do I find the critical values? y= 4/x + tan(πx/8) What I ...
- geometry/algebra - I asked this question yesterday, and I'm trying to understand...
- Math - Evaluate *Note - We have to find the exact value of these. That I know to...
- Trig - The set of solution(s) of 2 cos^2 (θ) - 13 cos(θ) + 6 = 0 that ...
- Precalc/Trig - Sorry there are quite a few problems, but I just need to know if ...
- Precalculus - Use one of the identities cos(t + 2πk) = cos t or sin(t + 2...