RRB NTPC Mains or Stage 2 Model Paper 4 with solutions

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Question : 18 of 120

Marks: +1, -0

If tan

x =3 / 4

, where 0º < x < 90º, then what is the value of sin x cos x?

$3/ 5$
$4/ 5$
$12 /25$
$13 /25$

Solution:

(c) Given, tan x =

3/ 4 0º< x < 90º

∴ sin x = {tan x ,}/ √{1 + tan^2 x}, 0° < x < 90°

= 3/4/ √{1+ 9/16} =3/4/√{25 /16} =3/5

and cos x = 1/ √{1+ tan^2 x} =1/√{1+[3/4]^2}=1/√ {16 +9 /16}=4/5

∴sin x cos x

3/5× 4/5×= 12 /25

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