## Trigonometry 7th Edition

B = $20^{\circ}$
in triangle ABC- Given data is- A = $80^{\circ}$ C = α + β = $80^{\circ}$ As we know that all the three angles of a triangle add up to 180 degrees, therefore- A + B + C = $180^{\circ}$ B = $180^{\circ}$ - $(C+A)^{\circ}$ B = $180^{\circ}$ - $(80+80)^{\circ}$ B = $180^{\circ}$ - $160^{\circ}$ B = $20^{\circ}$