# The size of an exterior angle of a triangle is the supplement of smaller of two opposite interior angles. If the greater of the opposite interior angles exceeds smaller by 30°, find the measure of the interior angles of the triangle.

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Respuesta :

Answer:

30° and 60°

Step-by-step explanation:

Let the interior angles be ∠x₁ (smaller) and ∠x₂ (larger), and the exterior angle ∠X.

Making the statements into equations :

Size of an exterior angle of a triangle is the supplement of smaller of two opposite interior angles ⇒ ∠X + ∠x₁ + ∠x₂ = 180° [Equation 1]

Greater of the opposite interior angles exceeds smaller by 30° :

∠x₂ = ∠x₁ + 30° [Equation 2]

By exterior angle property :

∠x₁ + ∠x₂ = ∠X [Equation 3]

Substituting Equation 3 in Equation 1 :

⇒ ∠x₁ + ∠x₂ + ∠x₁ + ∠x₂ = 180°

⇒ 2 (∠x₁ + ∠x₂) = 180°

⇒ ∠x₁ + ∠x₂ = 90°

∠x₂ = 90° - ∠x₁ [Equation 4]

Substituting Equation 4 in Equation 2 :

⇒ 90° - ∠x₁ = ∠x₁ + 30°

⇒ 2∠x₁ = 60°

⇒ ∠x₁ = 30°

Substituting the value of ∠x₁ in Equation 2 :

⇒ ∠x₂ = 30° + 30°

⇒ ∠x₂ = 60°

The measures of the interior angles are 30° and 60°

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