If $\tan \alpha = - \frac { 7 } { 24 }$

question 24

Multiple Choice

If $\tan \alpha = - \frac { 7 } { 24 }$ and $\beta = \frac { 3 } { 4 }$ for a second-quadrant angle $\alpha$ and a third-quadrant angle $\beta$ , find $\cos ( \alpha + \beta )$

• A) \(- \frac { 3 } { 11 }\)
• B) \(- \frac { 11 } { 4 }\)
• C) \(\frac { 4 } { 5 }\)
• D) \(\frac { 5 } { 4 }\)
• E) \(\frac { 3 } { 5 }\)