RRB NTPC 28 April 2016 Paper

Question : 89 of 100

Marks: +1, -0

If two supplementary angles are in the ratio of 4 : 5, find the ratio of the square of the first angle to the square of the second angle.

16 : 25
64 : 125
100 : 125
25 : 16

Validate

Solution:

(1) Ratio of supplementary angles= 4:5
Sum of supplementary angles= 180°
Hence, 4x + 5x = 180°
⇒9x = 180°
⇒x = 20°
First angle = 4x = 80°
Second angle = 5x =100°
Ratio of their squares

= { ( 80 ) ^ { 2 } }/ { ( 100 ) ^ { 2 } } = { 80 × 80 }/ { 100 × 100 } = \ { 64 }/ { 100 }

= { 16 }/ { 25 } ⇒ 16 : 25

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