Question

find the lettered angle in each case

Answer 1

Hi friend
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Your answer
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Here,

In ∆ABC,

Angle ACB = 180° - (Angle BAC + Angle ABC)

=> Angle ACB = 180° - (50° + 90°)

=> Angle ACB = 180° - 140° = 40°

Again,
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In ∆DEC ,

X = 180° - (Angle DEC + Angle ACB)

=> X = 180° - (100° + 40°)

=> X = 180° - 140° = 40°

HOPE IT HELPS