SOLUTION: given that x degrees is an angle in the First quadrant that 8sin^2 + 2cosx

SOLUTION: given that x degrees is an angle in the First quadrant that 8sin^2 + 2cosx - 5 = 0 a) find cos x b) find tan x

Question 1102187: given that x degrees is an angle in the First quadrant that 8sin^2 + 2cosx - 5 = 0
a) find cos x
b) find tan x
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
given that x degrees is an angle in the First quadrant that 8sin^2 + 2cosx - 5 = 0
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8sin^2 + 2cosx - 5 = 0
8(1-cos^2) + 2cosx - 5 = 0
8 - 8cos^2 + 2cos - 5 = 0
8cos^2 - 2cos - 3 = 0
(2cos + 1)*(4cos - 3) = 0
cos(x) = -1/2 (not in Q1)
cos(x) = 3/4
=================
a) find cos x
= 3/4
==============
b) find tan x
sin(x) = sqrt(1 - cos^2(x)) = sqrt(7)/4
tan = sin/cos
tan(x) = sqrt(7)/3
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