Question

Cos x + cos y = 4/5, cos x - cos y = 2/7 ⇒ 14 tan a)
0
b)
1/4
c)
5/4
d)
3/4

Answer 1

Answer:

Something wrong with the Question.

Explanation:

$cosx + cosy = \frac{4}{5} \\ cosx - cosy = \frac{2}{7}$

Therefore

$2cosx = \frac{4}{5} + \frac{2}{7}$

$=> 2cosx = \frac{28 + 10}{35}$

$=> cosx = \frac{38}{70} \\ => cosx = \frac{19}{35}$