If a and b are two angles in standard position in Quadrant I, find cos(a+b) for the given function values. sin a=4/5 and cos b=5/13
Accepted Solution
A:
First let's find the angles a and b.
We have then: sin a = 4/5 a = Asin (4/5) a = 53.13 degrees.
cos b = 5/13 b = Acos5 / 13 b = 67.38 degrees.
We now calculate cos (a + b). To do this, we replace the previously found values: cos ((53.13) + (67.38)) = - 0.507688738 Answer: -0.507688738 Note: there is another way to solve the problem using trigonometric identities.