Have you tried the double angle formulas?
Yes. It is just too hard and it would be nice if you would just explain it to me or show me an example. Please.
Hard? Why would anyone want to do something easy?
2cos^2x+cosx=cosx= cos(x)cos(x) - sin(x)sin(x) = cos²(x) - sin²(x)
2 cos^2 x+cosx=cos^2x-(1-cos^2x)
2 cos^2 x+cosx=2cos^2x-1
the only way to make these easy is to do dozens of them, not just the assignments. The double angle formulas are critical to know.
cos 2x + sin x=0
1 - 2sin^2 x + sin x = 0
rearrange things a bit to the usual order:
2sin^2 x - sin x - 1 = 0
(2sin x + 1)(sin x - 1) = 0
so, either sin x = -1/2 or sin x = 1
sin x = -1/2: x = 7pi/6 or 11pi/6
sin x = 1: x = pi/2
Thanks for your help you guys.
Answer this Question
Math, please help - Which of the following are trigonometric identities? (Can be...
Pre-Calculus - Find all solutions to the equation in the interval [0, 2pi) cos4x...
calculus - Find all solutions to the equation in the interval [0,2pi) Cosx-cos2x
identities trig? - find all solutions to the equation in the interval [0,2pie] ...
Advanced Functions/Precalculus - Trigonometry Questions 1.) Find the exaqct ...
Trigonometry - Find all solutions of the equation in the interval [0,2pi] ...
Trig - find all solutions to the equation √3 csc(2theta)=-2 Would the ...
Trig - Verify the identity: tanx(cos2x) = sin2x - tanx Left Side = (sinx/cosx)(...
Advanced Functions/Precalculus - Trigonometry Questions 1. Solve the equation ...
Trigonometry - Solve for x in the interval 0<=x<360: 1. 2sin2x+cosx =0 2. ...