In the figure, 2 AD = AB, P is the mid point of AB, Q is mid point of DR and PR∥BS. Then, DSRS=
AB AP
Given: i) Q and A are mid points of RD and PD respectively.
(ii) PR∥BS.
Since A is mid point and Q is mid point, AQ∥PR [mid-point theorem]
Also, PR∥BS, using equal intercept theorem, in ΔDBS,
DPPB=DRRS
⇒DPPB+1=DRRS+1
⇒DBPB=DSRS
We know that DBPB=3 because DA = AP = PB
So, DSRS=3