What is the value of 2cos2(75°) – 1?

Option (1)

Step-by-step explanation:

2cos²(75°) - 1 = cos2(75°) [By using identity 2cos²a - 1 = cos2a]

                      = cos(150°)

                      = cos(90 + 60)°

                      = -sin(60°)  [Since, cos(90 + θ) = -sinθ]

                      =

Therefore, solution of the given expression is .

Option (1) will be the correct option.

a

step-by-step explanation:

option (a)

step-by-step explanation:

step 1:   take 2 number whose product equal to 25..

and sum of those two number are -10

step: 2 for example here if we take 5,5 are the number,,

5*5=25

and

5+5=10

but we need -10

so if we take   -5,-5

so -5*-5=25

and -5+(-5)=-10

s0

come the equation

replace -10x by these number

like -5x -5x+25

take common

x(x-5)-5(x-5)=0

(x-5)(x-5)=0