12. In figure, ST Il QR, PS 2 cm and SQ 3 cm. What is the ratio ofthe

1.	12. In figure, ST Il QR, PS 2 cm and SQ 3 cm. What is the ratio ofthe area of ΔPQR to the area of Δ PST ?[CBSE 2009 (o.D), 2009 (cls3 RC and area of A ABC 81 cm2, find the area of
Answer» ST \|\| RQ PS= 3 cm SR = 4cm We know that the ratio of areas of two similar triangles is equal to the ratio of squares of their corresponding sides. ar(∆PST) /ar(∆PRQ)= (PS)²/(PR)² ar(∆PST) /ar(∆PRQ)= 3²/(PS+SR)² ar(∆PST) /ar(∆PRQ)= 9/(3+4)²= 9/7²=9/49 Hence, the required ratio ar(∆PST) :ar(∆PRQ)= 9:49

12. In figure, ST Il QR, PS 2 cm and SQ 3 cm. What is the ratio ofthe area of ΔPQR to the area of Δ PST ?[CBSE 2009 (o.D), 2009 (cls3 RC and area of A ABC 81 cm2, find the area of

Answer»

ST || RQ

PS= 3 cm

SR = 4cm

We know that the ratio of areas of two similar triangles is equal to the ratio of squares of their corresponding sides.

ar(∆PST) /ar(∆PRQ)= (PS)²/(PR)²

ar(∆PST) /ar(∆PRQ)= 3²/(PS+SR)²

ar(∆PST) /ar(∆PRQ)= 9/(3+4)²= 9/7²=9/49

Hence, the required ratio ar(∆PST) :ar(∆PRQ)= 9:49