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Find the size of each lettered angle in the following figure:

Find the size of each lettered angle in the figure. Rectilinear Figures, ML Aggarwal Understanding Mathematics Solutions ICSE Class 9.

Rectilinear Figures

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Answer

As ED is a straight line, we have

⇒ 60° + ∠AED = 180° [Linear pair]

⇒ ∠AED = 180° - 60° = 120°

Also, as CD is a straight line

⇒ 50° + ∠BCD = 180° [Linear pair]

⇒ ∠BCD = 180° – 50°

⇒ ∠BCD = 130°

In pentagon ABCDE, we have

⇒ ∠A + ∠B + ∠AED + ∠BCD + x = 540° [Sum of interior angles of pentagon is 540°]

⇒ 90° + 90° + 120° + 130° + x = 540°

⇒ 430° + x = 540°

⇒ x = 540° - 430°

⇒ x = 110°

Hence, value of x = 110°.

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