If tan "" (alpha )/(2) and tan "" (beta...

If ` tan "" (alpha )/(2) and tan "" (beta)/( 2)` are the roots of the equation `8x ^(2) -26x + 15 =0,` then find the value of `cos (alpha + beta).`

A

`-627/725`

B

`627/725`

C

`-1`

D

none of these

Verified by Experts

The correct Answer is:

A

TRIGONOMETRIC RATIOS AND IDENTITIES
OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|60 Videos
TRIGONOMETRIC RATIOS AND IDENTITIES
OBJECTIVE RD SHARMA ENGLISH|Exercise Section II - Assertion Reason Type|13 Videos
TRIGONOMETRIC EQUATIONS AND INEQUATIONS
OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|60 Videos

Similar Questions

Explore conceptually related problems

If "tan"(alpha)/(2) and "tan"(beta)/(2) are the roots of the equation 8x^(2)-26x+15=0 , then find the value of "tan"((alpha+beta)/(2))

If alpha,beta are the roots of the equation x^(2)+x+1=0 , find the value of alpha^(3)-beta^(3) .

If alpha and beta are the roots of the equation x^2+4x + 1=0(alpha > beta) then find the value of 1/(alpha)^2 + 1/(beta)^2

If alpha and beta are the roots of the quadratic equation x^(2) - 4x - 6 = 0 , find the values of alpha^(2) + beta^(2) .

If alpha and beta are roots of the equation a cos theta + b sin theta = c , then find the value of tan (alpha + beta).

If tan alpha tan beta are the roots of the equation x^2 + px +q =0(p!=0) then

If alpha and beta are roots of the equation 2x^(2)-3x-5=0 , then the value of (1)/(alpha)+(1)/(beta) is

If alpha and beta are roots of the equation x^(2)-2x+1=0 , then the value of (alpha)/(beta)+(beta)/(alpha) is

If alpha,beta are the roots of the equation x^(2)-2x-1=0 , then what is the value of alpha^(2)beta^(-2)+alpha^(-2)beta^(2) ?

If alpha and beta (alpha gt beta) are the roots of x^(2) + kx - 1 =0 , then find the value of tan^(-1) alpha - tan^(-1) beta