Solution:

Consider AB as the boy and CD as the wall which is at a distance of 2.1 m

AB = 1.54 m

CD = 3.64 m

BD = 2.1 m

Construct AE parallel to BD

ED = 1.54 m

CE = 3.64 – 1.54 = 2.1 m

AE = BD = 2.1 m

In right triangle CAE

tan θ = CE/AE

So we get

tan θ = 2.1/2.1

tan θ = 21/21

tan θ = 1

We know that

tan 45⁰ = 1

We get

θ = 45⁰

Hence, the angle of elevation of the sun is 45⁰.