Question

If tan x =3/4

then the value of cos 2x is :
A)
(A)
(B)
5
(C)
7
25
(D) None of these​

Answer 1

Answer:

cos2x =1-tan^x/1+tan^x

Put value tan x 3/4

=1-(3/4)^÷1+(3/4)^

=1-9/16÷1+9/16

=7/16 ÷ 25/16

7/16*16/25

7/25answer

Answer 2

Given:

$tanx=\frac{3}{4}$

we have to find the value of $cos2x$.

we also know the formula as: $cos2x=\frac{1-tan^{2} }{1+tan^{2} x}$

now place the value of $tanx$ in above, we get:

$cos2x=\frac{1-(\frac{3}{4} )^{2} }{1+(\frac{3}{4} )^{2} }$

$cos2x=\frac{1-\frac{9}{16}}{1+\frac{9}{16} }$

$cos2x=\frac{16-9}{16+9}$

$cos2x=\frac{7}{25}$

The value of $cos2x=\frac{7}{25}$.