Cords AB and CD of circle intersect externally at P. If AB = 7cm, CD = 1cm and PD = 5cm, then the lenth of PB (in cm) is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 3
Here AB = 7 cm, CD = 1 cm, PD = 5 cm and PB = x cm
PB × PA = PD × PC
⇒ x × (x + 7) = 5 × (5 + 1)
⇒ x2 + 7x - 30 = 0
⇒ (x + 10) ( x - 3) = 0
⇒ x = -0 can't possible
PB = x = 3 cm