Q9 of 23 Page 87

In ΔABC, A + B = 70° and B + C = 135°. Find the measure of each angle of the triangle.

Given A + B = 70° and B + C = 135°


We know that sum of the angles of a triangle is 180°.


A + B + C = 180° …I


Also, A + B + B + C = 70° + 135°


(A + B + C) + B = 205°


From I,


180° + B = 205°


B = 205° - 180°


B = 25°


Putting in given equations,


A + B = 70° and B + C = 135°


A + 25° = 70° and 25° + C = 135°


A = 45° and C = 110°


So, the angles of the triangle are 45°, 25° and 110°.


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