Question

In a quadrilateral ABCD, the measure of the three angles A, B and C of the quadrilateral is 110°, 70° and 80°, respectively. Find the measure of the fourth angle.​

Answer 1

We know That sum of all angles of a quadrilateral is equal to 360°

=> A+B+C+D=360°

=> 110°+70°+80°+D=360°

=> 260°+D=360°

=>D=360°-260°

=> D = 100°

∴ The fourth angle is 100°

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Answer 2

Answer:

Angle D =100°

Step-by-step explanation:

Since the sum of all the angles of a quadrilateral is 360°

Therefore,

angle A + angle B +angle C+ angle D=360

110 +70 + 80 + angle D =360

angle D = 360 - (110+70+80)

angle D = 100