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**xwrathbringerx** a) In a quadrilateral ABCD, P and R are the midpoints of AB and CD respectively. Also Q and S are points on the sides BC and DA respectively such that BQ = 2QC and DS = 2SA. Prove that the area of the quadrilateral PQRS equals S/2 where S is the area of the quadrilateral ABCD.

b) In a triangle ABC, AC = 2AB and BC/BA = 3/2. H is the foot of the perpendicular from B to AC. Prove that CH/AH = 21/11.

Ummm for b)

let a = AB; then 2a = AC and 3a/2 = BC

let b = AH; then 2a - b = CH

let h = BH; then h^2 = a^2 - b^2 and h^2 = (3a/2)^2 - (2a - b)^2

that's all i could get. Can anyone help?