Find the exact value of cos(a+b) if cos a=-1/3 and cos b=-1/4 if the terminal side if a lies in quadrant 3 and the terminal side of b lies in quadrant 2

cos(a + b) =

Step-by-step explanation:

cos(a + b) = cos(a).cos(b) - sin(a).sin(b) [Identity]

cos(a) =

cos(b) =

Since, terminal side of angle 'a' lies in quadrant 3, sine of angle 'a' will be negative.

sin(a) = [Since, sin(a) = ]

         =

         =

Similarly, terminal side of angle 'b' lies in quadrant 2, sine of angle 'b' will be  negative.

sin(b) =

         =

         =

By substituting these values in the identity,

cos(a + b) =

                =

                =

                =

Therefore, cos(a + b) =

nope

step-by-step explanation:

no idea

step-by-step explanation: