a Find all solutions in the interval 0 2 rounded to five dec
(a) Find all solutions in the interval [0, 2), rounded to five decimal places. (Enter your answers as a comma-separated list.)
4 cos 2 = 2
theta=
(b) Find the exact value of
cos(2tan^-1 4/3)
(c)Rewrite the expression as an algebraic function of x and y.
cos(sin1 x tan1 y)
Solution
4 cos 2 theta = 2
cos 2 theta = 2/4
cos 2 theta = 1/2
theta = ( pi + 6pi*n ) / 6 , (5pi + 6pi*n )/ 6
solutions are
theta = 7pi/6 , 5pi/6 , pi/6 , 11pi/6
b) cos ( 2tan^-1 4/3)
let tan^-1 4/3 = x
tan x = 4/3
cos x = 3/5
sin x = 4/5
cos ( 2tan^-1 4/3) = cos 2 x
applying double angle formula
cos 2x = cos^2 x - sin^2 x = (3/5)^2 - (4/5)^2 = 9/25 - 16/25 = -7/25
cos ( 2tan^-1 4/3) = -7/25
