Aconjecture and the flowchart proof used to prove the conjecture are shown. given: m∠qrs=76° prove: △pqr is an obtuse triangle.

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Given: m∠QRS=76°

Prove: △PQR is an obtuse triangle.

Proof:- ∠ORS=76° [given]

∠PRQ and ∠QRS are supplementary . [Linear pair postulate.]

m∠PRQ+76°=180° [Substitution property of equality]

m∠PRQ=104°  [Subtraction property of equality]

∠PRQ is an obtuse angle [Definition of obtuse angle]

ΔPQR is an obtuse triangle.[Definition of obtuse triangle]