Area and Perimeter Practice Test 4

Question : 2 of 40

Marks: +1, -0

A brick, 5 cm thick (high) is placed against a wheel to act for a stop. The horizontal distance of the face of the brick stopping the wheel from the point, where the wheel touches the ground is 15 cm. Find the radius of the wheel.

20 cm
25 cm
30 cm
35 cm

Validate

Solution:

Let ABCD is a brick in which AD = 5 cm and also AE = 15 cm
If radius of the wheel = OD = OE = r cm
From the figure, OF = r – 5 cm, FD = 5 cm
Now, from the right Δ OFD,

OD^2 – OF^2

FD^2

⇒

r^2 – (r – 5)^2

= 152
⇒ 10r – 25 = 225
⇒ 10r = 250
⇒ r =

{250}/{10}

= 25 cm

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