The diagram shows a wedge in the shape of a prism.
Angle BCF is a right angle.
A string runs diagonally across the wedge
from A to F.
Calculate the length A F.
Give your answer correct to 3 significant figures

11.547 cm

Step-by-step explanation:

Triangle ABC is a right triangle. BC and AB are x cm long. From Pythagorean theorem:

AC² =  x² + x² = 2x²

Triangle ACF is a right triangle. CF is x cm long. From Pythagorean theorem:

20² = AC² + x²

20² = 2x² + x²

20² = 3x²

√(20²/3) = x

x = 11.547 cm

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°