ion 92 Question 060 l Incorrect Find an identity for cos 4 i

ion 9.2, Question 060 l Incorrect. Find an identity for cos 4 in terms of cost. sin log LINK TO TEXT All R

Solution

cos(4 theta)= cos2(2 theta) = 2 cos²2 theta -1 = 2(2 cos²theta-1)²-1= 2(1+4 cos⁴theta -4cos²theta)-1

                                                                 = 2+8cos⁴theta -8cos²theta -1= 8cos⁴theta -8cos²theta +1