∠BAC of △ABC is obtuse and AB=AC. P is a point on BC such that PC=12 cm. PQ and PR are perpendiculars to sides AB and AC respectively. If PQ=15 cm and PR=9 cm, then the length of PB (cm) is
Given: AB=AC, PQ⊥AB and PR⊥AC
Since, AB=AC
∠ABC=∠ACB...(I) (Isosceles triangle property)
Now, In △PBQ and △PRC
∠PBQ=∠PCR (From I)
∠PQB=∠PRC (Each 90°)
∠QPB=∠RPC (Third angle)
Thus, △QPB∼△RPC (AAA rule)
Hence, PQ/PR=PB/PC
15/9=PB/12
PB=15×12/9
PB=20 cm