SOLUTION: This one is too hard and I can't get it. . . Find the exact value of: ' cos ( tan^-1 (4/3) + cos^-1 (12/13 ) ) ' Thank You

Algebra ->  Trigonometry-basics -> SOLUTION: This one is too hard and I can't get it. . . Find the exact value of: ' cos ( tan^-1 (4/3) + cos^-1 (12/13 ) ) ' Thank You      Log On


   

Question 513390: This one is too hard and I can't get it. . .
Find the exact value of:
'
cos ( tan^-1 (4/3) + cos^-1 (12/13 ) )
'
Thank You
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
cos (A + B) = (cos A)cos B - (sin A)sin B

for a 3-4-5 triangle ___ tan^-1 (4/3) = cos^-1 (3/5) = sin^-1 (4/5)

for a 5-12-13 triangle ___ cos^-1 (12/13) = sin^-1 (5/13)