Monday
March 30, 2015

Homework Help: Math - Trig - Double Angles

Posted by Anonymous on Saturday, November 17, 2007 at 6:17pm.

Prove:
cos4x = 8cos^4x - 8cos^2x + 1

My Attempt:
RS:
= 4cos^2x (2cos^2x - 1) + 1
= 4 cos^2x (cos2x) + 1

LS:
= cos2(2x)
= 2cos^2(2x) - 1
= (cos^2(2)) - cos^2(2x)) - 1





-----





Prove:
8cos^4x = cos4x + 4cos2x + 3

My Attempt:
RS:
= cos2(2x) + 4cos(2x) + 3
= 2cos^2(2x) - 1 + 2(4)cos^2(2x) - 1 + 3

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Trigonometry - Need help solving problems using the Trigonometric Identities: ...
trig - Prove that cos4x=8cos^4x-8cos^2x+1 so I'm guessing you begin with the ...
Pre-Calculus - Find all solutions to the equation in the interval [0, 2pi) cos4x...
Math - Solving Trig Equations - What am I doing wrong? Equation: sin2x = 2cos2x ...
Math - Solving for Trig Equations - Solve the following equation for 0 less than...
math - cosA= 5/9 find cos1/2A are you familiar with the half-angle formulas? the...
trig - how can you confirm the identity cos^4x = (1/8)(3+ 4cos2x+ cos4x) and ...
math - Prove the identity: 1-cos2x/sin2x = 1+tanx/1+cotx I simplified the RS to ...
Trig....... - I need to prove that the following is true. Thanks (2tanx /1-tan^x...
Math - Trig - Double Angles - Prove: sin2x / 1 - cos2x = cotx My Attempt: LS: = ...

Members