जर \(\tan A = \frac{{15}}{8}\) आणि \(\tan B = \frac{{7}}{24}\), तर cos(A + B) = ? A. \(\frac{{87}}{{425}}\) B. \(\frac{{304}}{{425}}\) C. \(\frac{{297}}{{425}}\) D. \(\frac{{416}}{{425}}\)

उत्तर दाखवा आणि स्पष्टीकरण

उत्तर: (A) A

स्पष्टीकरण

tan A = 15/8 gives sin A = 15/17, cos A = 8/17; tan B = 7/24 gives sin B = 7/25, cos B = 24/25. cos(A + B) = cos A cos B − sin A sin B = (192 − 105)/425 = 87/425.