Question

How do I solve this?

Answer 1

The interior angles of any triangle always sum to 180°.

In the triangle, angles C and D are labeled congruent, so the missing angle has measure

180° - 2 (6x - 5)°

This angle is supplementary to the one labeled (11x + 1)°, which means

180° = (11x + 1)° + (180° - 2 (6x - 5)°)

Solve for x :

180° = (11x + 1)° + 180° - 2 (6x - 5)°

0 = (11x + 1)° - 2 (6x - 5)°

0 = (11x)° + 1° - (12x)° + 10°

(12x - 11x)° = 1° + 10°

x° = 11°

x = 11