we are supposed to assume ratio of similar triangles (since he is looking at mirror, angle of incendence=angle of reflection so all 3 angles are same and the triangles are similar)
use ratio
ratio of height of small triangle to base of small triangle=ratio of height of large triangle to base of large triangle
so6:2=h:246/2=h/243=h/24multiply both sides by 2472=hthe tree is 72ft tall
answer is D