What you need to know

The sloping section, the 1,210 mm horizontal distance and the 340 mm vertical drop form a right-angled triangle. Use inverse tangent to find the small slope angle. Angles on a straight line add to 180 degrees, while angles around a point add to 360 degrees.

Tip 1

Start with gamma, the small angle between the slope and the ground.

Tip 2

Use gamma to find beta. Alpha is the reflex angle around the other side of the joint, so alpha and beta must add to 360 degrees.

How to solve it

Use tan(gamma) = opposite / adjacent = 340 / 1,210.

gamma = tan^-1(340 / 1,210) = 15.68 degrees, which rounds to 16 degrees.

Beta and gamma form a straight line, so beta = 180 - 15.68 = 164.32 degrees, which rounds to 164 degrees.

Alpha and beta are the two angles around the joint, so alpha = 360 - 164.32 = 195.68 degrees, which rounds to 196 degrees.

Check: 195.68 + 164.32 = 360 degrees.