Quadrilateral ABCD has the following angle measures:

m∠A = 105°, m∠B = ?°, m∠C = 34°, m∠D = 90°

What is m∠B?


pleeeeease help!!

Respuesta :

Answer:

131°

Step-by-step explanation:

Sum of all angles of a quadrilateral = 360°

We can find the unknown angle ∠B, by subtracting the sum of the angles ∠A, ∠C, ∠D from 360°.

∠A + ∠B + ∠C + ∠D = 360

105 + ∠B + 34 + 90  = 360

           ∠B +  229      = 360

                     ∠B       = 360 - 229

                           ∠B = 131°