
William W. answered 11/04/20
Tutor
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Experienced Tutor and Retired Engineer
The picture looks like this:
To find θ1 just use your calculator θ1 = sin-1(5/8) = 38.7°. To find θ2 you must be familiar with the cyclic nature of the trig functions and the unit circle. But, simply enough, θ2 = 180° - θ1 = 141.3°