Practicing Success
If $cos(A - B) =\frac{\sqrt{3}}{2}$, and $cos(A + B) = 0$, where A and B are positive acute angles and A ≥ B, then the measures of A and B are: |
80° and 10° 60° and 30° 70° and 20° 50° and 40° |
60° and 30° |
We are given that , cos ( A - B ) = \(\frac{ √3 }{2}\) & cos ( A + B ) = 0 { we know , cos 30º = \(\frac{ √3 }{2}\) & cos 90º = 0 } So , A - B = 30º ----(1) A + B = 90º ---(2) On adding 1 and 2. 2A = 120º A = 60º Now, 60º - B = 30º B = 30º Ans :- 60º and 30º |