Practicing Success
If $0^\circ < A, B < 45^\circ, \cos(A + B) = \frac{24}{25}$ and $\sin(A - B) = \frac{15}{17}$, then $\tan 2A$ is |
1 0 $\frac{416}{87}$ $\frac{213}{4}$ |
$\frac{416}{87}$ |
tan2A = tan ( A + B + A - B ) ATQ, cos (A+B) = \(\frac{24}{25}\) By using pythagoras theorem, P² + B² = H² P² + 24² = 25² P² = 625 - 576 = 49 P = 7 And sin ( A - B ) = \(\frac{15}{17}\) P² + B² = H² 15² + B² = 17² B = 8 { using tan (x + Y ) = \(\frac{tanX + tanY }{1 - tanX.tanY}\) } Now, tan2A = tan ( A + B + A - B ) = \(\frac{tan(A+B) + tan(A-B) }{1 - tan(A+B) .tan(A-B) }\) = \(\frac{7/24+ 15/8 }{1 - 7/24 × 15/8 }\) = \(\frac{52/24 }{ 1 - 35/64 }\) = \(\frac{416 }{ 87 }\) |