SSC CHSL Model Paper 14

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Question : 61 of 100

Marks: +1, -0

If x and y are positive acute angles, x + y < 900 and sin (2x - 20°) = cos (2y + 20°) , then the value of sec (x + y) is

$√2$
$1/√2$
1
0

Solution:

\sin (2x - 20°) = \cos (2y + 20°)

⇒

2x - 20 = 4 5 °

and

2y + 2 0° = 4 5 °

⇒

x = 3 2 .5 ° ⇒ y = 1 2.5 °

\sec (x + y) = \sec 45 ° = √2

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