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In the Given Figure, the Directed Lines Are Parallel to Each Other. Find the Unknown Angles. - Mathematics

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Question

In the given figure, the directed lines are parallel to each other. Find the unknown angles.

Sum

Solution

∵ Lines are parallel

∠a = ∠1 and ∠c = ∠2 .........(alternate angles)

But ∠1 + 115° = 180° .........(linear pair)

∴ ∠1 = 180°− 115° = 65°

Similarly ∠2 + 120° = 180°

∴ ∠2 = 180°− 120° = 60°

∴ ∠a = ∠1 = 65°, ∠c = ∠2 = 60°

But a + c + c = 180° ............(angles on a line)

⇒ 65° + b + 60° = 180°

⇒ b + 125° = 180°

⇒ b = 180°− 125° = 55°

Hence a = 65°, b = 55°, c =60°

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Properties of Parallel Lines
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Chapter 14: Lines and Angles (Including Construction of angles) - Exercise 14 (B)

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Selina Concise Mathematics [English] Class 7 ICSE
Chapter 14 Lines and Angles (Including Construction of angles)
Exercise 14 (B) | Q 6.09
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