KVPY SX SB Exam 19-Nov-2017 Question Paper

Question : 19 of 120

Marks: +1, -0

A spherical ball is kept at the corner of a rectangular room such that the ball touches two (Perpendicular) walls and lies on the floor. If a point on the sphere is at distances of 9, 16, 25 from the two walls and the floor, then a possible radius of the sphere is

Validate

Solution:

(r -9)^2 + (r -16)^2 + (r -25)^2 = r^2

solving this

2r^2-100 r + 962 = 0

r^2-50 r + 481 = 0

r = 37, r = 13
possible radius = 13
According to option

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