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Question
Find, giving a reason, the unknown marked angles, in a triangle drawn below:
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Solution
We know that,
Exterior angle of a triangle is always equal to the sum of its two interior opposite angles (property)
x+115° = 180°
(linear property of angles)
⇒ x = 180°- 115° ⇒ x = 65°
∴115° = x + y
⇒ 115° = 65° + y
⇒ y= 115° – 65° =50°
y = 50°
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