Question

Find B if A=70° and a + b = 80°

Answer 1

B=30°

Explanation:

Recall that the sum of interior angles of a triangle equals to 180°. So basically

`A+B+\alpha+\beta=180^(\circ)`

`\implies B + {70}^( \circ) + {80}^( \circ) = {180}^( \circ) \\ \implies B = {180}^( \circ) - {150}^( \circ) \\ \implies B = \boxed{{30}^( \circ) }`