Question

In triangle ABC, AD _I_ BC. Prove that AB²-BD² = AC²-CD²​

Answer 1

In triangle ABC, AD is perpendicular to BC. Proof: In triangle, ABD;ADsquare=ABsquare -BDsquare- (1eq). In triangle,ADC:ABsq=ACsq-CDsq(2eq). From (1eq) and (2eq),we get:ABsq-BDsq=ACsq-CDsq.