Friday

January 30, 2015

January 30, 2015

Posted by **Anonymous** on Thursday, May 3, 2007 at 1:43pm.

are you familiar with the half-angle formulas?

the one I would use here is

cos A = 2cos^2 (1/2)A - 1

5/9 + 1 =2cos^2 (1/2)A

14/9 =2cos^2 (1/2)A

cos (1/2)A = √(7)/3

**Answer this Question**

**Related Questions**

Math - Solving Trig Equations - What am I doing wrong? Equation: sin2x = 2cos2x ...

Trigonometry - Need help solving problems using the Trigonometric Identities: ...

Trigonometry - I need to prove that the following is true. Thanks. csc^2(A/2)=...

Math, derivatives - f(x) = x² + 2Cos²x, find f ' (x) a) 2(x+cos x) b) x - sin x ...

math (trig) - i have some problems doing trig the first one is: Show that cos(x/...

math - how would you find the angle to (3)^.5sin(2x)-2cos(2x)+2sin^2(x)=1 I know...

Trig - If cosx = 10/19 an pi < x < 2pi, find the exact value of cos x/2 ...

Math - Solving for Trig Equations - Solve the following equation for 0 less than...

MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...

Math - Trig - Double Angles - Prove: cos4x = 8cos^4x - 8cos^2x + 1 My Attempt: ...