How do you find cos theta?

tan #theta# = #4sqrt(3)# and 0< #theta#< #pi/2#

2 Answers
David Tran · 1s2s2p
Jan 22, 2018

#cos θ = 1/7#

Explanation:

#theta=tan^-1 (4√3)~~1.43^"c"#

#cos(1.43^"c") = 1/7#

Nghi N
Feb 1, 2018

cos t = 1/7

Explanation:

Use trig identity:
#cos^2 t = 1/(1 + tan^2 t)#
In this case:
#cos^2 t = 1/(1 + 48) = 1/49#
#cos t = +- 1/7#
Because t is in Quadrant 1, therefor, cos t is positive.
#cos t = 1/7#

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