In the given figure we have to prove that Δ ADE and Δ FGC are similar.
Now from Δ ADE and Δ GFC we have,
∠AED=∠GFC [right-angles],
∠DAE=∠FGC [ ∵ AD∥GF andAC intersector, similar angles].
Then ∠ADE=∠GCF [Remaining angles equal by 180∘ rule].
∴ΔADE is similar to ΔGFC.[By AA test] [henceproved]