Question

The three angles of a quadrilateral are 6odegrees,80degreesand120degrees.fiind the fourth angle

Answer 1

Sum of all the angles of a quadrilateral are 360 degrees
60+80+120+x=360
260+x=360
x=360-260
=100 degrees
Verification
60+80+120+100=360
360=360

Answer 2

Solution :

Let <A = 60° , <B = 80° , <C = 120° , <D = x°

are four angles of a quadrilateral ABCD.

We know that ,

<A + <B + <C + <D = 360°

=> 60° + 80° + 120° + x = 360°

=> 260° + x = 360°

=> x = 360° - 260°

=> x = 100°

Therefore ,

Fourth angle = <D = x = 100°

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