Posted by Haley on Tuesday, November 20, 2012 at 3:21pm.
cos^2x-sin^2 x+1=cos x
- pre-calc help !!!!!!! - Damon, Tuesday, November 20, 2012 at 3:33pm
sin^2 x = 1 - cos^2 x
so we have
cos^2 x - 1 + cos^2 x + 1
2 cos^2 x
on the left
2 cos^2 x = cos x
cos x = 1/2
x = 60 degrees or pi/3 radians
300 degrees or 5 pi/3 radians
- pre-calc help !!!!!!! - Reiny, Tuesday, November 20, 2012 at 3:43pm
from Damon's middle section:
2cos^2 x - cosx = 0
cosx(2cosx - 1) = 0
cosx = 0 or cosx = 1/2
so from cosx=1/2 we have the 2 answers that Damon gave
from cosx = 0 , we also have
x = 90° or x = 270°
x = π/2 or x = 3π/2
Answer This Question
More Related Questions
- pre-cal - Simplify the given expression........? (2sin2x)(cos6x) sin 2x and cos ...
- Calc. - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x ln...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- Math, Pre-Calc - the original problem was: Solve: sin(3x)-sin(x)=cos(2x) so far ...
- algebra - Can someone please help me do this problem? That would be great! ...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- pre calc trig check my work please - sin x + cos x -------------- = ? sin x sin ...
- calculus - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x...