Question

The three angles of a quadrilateral are 60degrees, 80degrees,&120degrees? Find the fourth angles?

Answer 1

the three angles are 60,80,120
suppose 4th as x
sum of 4 angles = 360
60+80+120+x=360
260+x= 360
x=360-260
x=100

so, 4th angle =100
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Answer 2

Hey there!

By angle sum property of a Quadrilateral:

∠A + ∠B + ∠C + ∠D = 360°

60° + 80° + 120° + ∠D = 360°

∠D = 360° - 260° 

     = 100°

Hence,
The angle of Fourth vertex is = 100°

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