Explanation
Step 1: Find x using angle sum property.
We know, by angle sum property, the sum of angles of a quadrilateral is 360o. The given angles are 70o,60o,90o,x. [Linear pairs are supplementary] Then, 70o+60o+90o+x=360o.
Therefore, the unknown angle is:
⇒ 360o−(70o+60o+90o)=x
⇒ x=360o−220o
=140∘.
Therefore, the unknown angle is x=140o.
Hence, option B is correct.
Let the four angles be ∠A,∠B,∠C and ∠D .
Then ∠A=120o,∠B=73o,∠C=80o .
We know, by angle sum property, the sum of angles of a quadrilateral is 360o.
⟹ ∠A+∠B+∠C+∠D=360o.
Then, ∠D will be given by:
∠D=360o−∠A−∠B−∠C
⇒∠D=360o−120o−73o−80o
⇒∠D=360−273o
⇒∠D=87o.
The measure of fourth angle is 87o.
Therefore, option A is correct.
Here, the sum of angle will be =110o+80o+90o+105o=385o>360o.
We know, by angle sum property, the sum of angles of a quadrilateral is 360o. The given angles are 50o,130o,120o,x. Then, 50o+130o+120o+x=360o.
⇒ 360o−(50o+130o+120o)=x∘
⇒ xo=360o−300o=60∘.
Therefore, the unknown angle is xo=60o.
Hence, option C is correct.
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