Question

Find the angle Ө
in triangle ABC

Answer 1

`\cos(\theta )=\cfrac{\stackrel{adjacent}{4}}{\underset{hypotenuse}{5}} \implies \cos^(-1)(~~\cos( \theta )~~) =\cos^(-1)\left( \cfrac{4}{5} \right) \\\\\\ \theta =\cos^(-1)\left( \cfrac{4}{5} \right)\implies \theta \approx 36.87^o`

Make sure your calculator is in Degree mode.