Given: Parallelogram STAR, TK ⟂ SR and TL ⟂ AR

Prove: TS / TA = SK / AL

△TKS ~ △TLA
∠S = ∠A
Definition
Parallelogram STAR, TK ⟂ SR and TL ⟂ AR
Given
TS / TA = SK / AL
The opposite sides and angles of a parallelogram are equal
∠TKS = ∠TLA
AA similarity
All right angles are equal