Wednesday

October 22, 2014

October 22, 2014

Posted by **Denise** on Sunday, May 9, 2010 at 12:37pm.

- trig -
**Reiny**, Sunday, May 9, 2010 at 1:50pmSo sinx = 1/2 and x must be in 2nd quadrant.

then by Pythagoras cos x = -√3/2

we know cos 2A = 1 - 2sin^2A

then cosx = 1 - 2sin^2(x/2)

-√3/2 = 1 - 2sin^2(x/2)

2sin^2(x/2) = 1 + √3/2

sin^2(x/2) = (2 + √3)/4

sin(x/2) = (√(2+√3))/2

**Answer this Question**

**Related Questions**

trig - on the same set of axes: (0 degrees is greater than or equal to x and x ...

trig - I have to retype this. For which angles theta, with 0 degrees less than/...

trig - Sketch the graph of f(x)=sin(x+30 degrees) and g(x)=cos2x in the same ...

math - For which angles beta, with 0 degrees less than/equal to beta less than/...

trig help - I need help finding sinA if cosA=(-3/5) and A is greater than 90 ...

trig - sin2 theta = cos theta, 90 degrees less than or equal to thetha greater ...

trig - How do you express in terms of angles less than 90 degrees? sin 120 ...

Trig(continued) - 2)Find the solution of sin2 theta = cos theta if 0 -< theta...

Math - Solving Trig Equations - Solve each equation on the interval: 0 is less ...

Precalculus/Trig - I can't seem to prove these trig identities and would really ...