Question

a ladder is 10m long and is leaning on the wall, its foot is 5 away from the wall. find the angle it make with ground

Answer 1

make right angle triangle

it's hypotenuse will be equal to height of ladder and base be 5m

now find angle as like this
$\cos( \alpha ) = \frac{5}{10} \\ \cos( \alpha ) = \frac{1}{2} \\ \alpha = \frac{\pi}{3}$
angle will be equal to 60°

Answer 2

cos
$\cos( \alpha ) = 5 \div 10$
$\alpha = 30 \: degree$