Focus of the parabola y2=42x is (α,0) Here, a=‌
1
4
and K=0 So, equation of parabola is y2=x As, the line x=2y+3 cuts the parabola y2‌=x y2‌=2y+3 ⇒y2−2y−3‌=0 y2−3y+y−3‌=0 y‌=3,−1 If y=3, then x=9 and If y=−1, then x=1 The two intersecting points P and Q are (9.3) and (1,−1) PQ‌=√(9−1)2+(3+1)2 ‌=√64+16=√80 ‌=4√5 ‌=16a√5‌‌[∵a=‌