Question

Find the value of the unknown interior angle x in the following figures:

Answer 1

(i) $x + 50° = 115°$ (Exterior angle theorem)
$x = 115° - 50° = 65°$

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(ii) $70° + x = 100°$ (Exterior angle theorem)
$x = 100° - 70° = 30°$

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(iii) $x + 90° = 125°$ (Exterior angle theorem)
$x = 125° - 90° = 35°$

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(iv) $x + 60° = 120°$ (Exterior angle theorem)
$x = 120° - 60° = 60°$

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(v) $x + 30° = 80°$ (Exterior angle theorem)
$x = 80° - 30° = 50°$

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(vi) $x + 35° = 75°$ (Exterior angle theorem)
$x = 75º - 35º = 40°$