Question

the three angles of a quadrilateral are 75°,80°,120°.find the measure of fourth angle​

Answer 1

Let the unknown angle be z.

<1=75°

<2=80°

<3=120°

<4=z

<1+<2+<3+<4=360° {All the angles of a quadrilateral add upto 360°}

75°+80°+120°+z=360°

275°+z=360°

z=360°-275°

z=85°

Therefore, <4=z=85°

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