Mathematics
In a triangle ABC, ∠A = x°, ∠B = (3x - 2)° and ∠C = y°. Also, ∠C - ∠B = 9°. Find all the three angles of the △ABC.
Triangles
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Answer
Given: In Δ ABC, ∠A = x°, ∠B = (3x - 2)°, ∠C = y° and ∠C - ∠B = 9°.
⇒ y° - (3x - 2)° = 9°
⇒ y° - 3x° + 2° = 9°
⇒ y° - 3x° = 9° - 2°
⇒ y° - 3x° = 7°
⇒ y° = 7° + 3x°…………….(1)
We know that sum of all angles of the triangle is 180°.
⇒ ∠A + ∠B + ∠C = 180°
⇒ x° + (3x - 2)° + y° = 180°
⇒ x° + 3x° - 2° + y° = 180°
⇒ 4x° + y° = 180° + 2°
⇒ 4x° + y° = 182° ……………(2)
Substituting the value of y° from equation (1) in equation (2), we get:
⇒ 4x° + 7° + 3x° = 182°
⇒ 7x° = 182° - 7°
⇒ 7x° = 175°
⇒ x° =
⇒ x° = 25°
∠A = x° = 25°
Substituting the value of x° in equation (1),
y° = 7° + 3x°
⇒ y° = 7° + 3 25°
⇒ y° = 7° + 75°
⇒ y° = 82°
∠C = y° = 82°
∠B = (3x - 2)° = (3 25 - 2)°
= (75 - 2)° = 73°
Hence, the value of ∠A = 25°, ∠B = 73° and ∠C = 82°
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