Q2 of 34 Page 170

In a triangle ABC, ∠A = 80° and AB = AC, then ∠B is ______

In the given ∆ABC,


∠A = 80° and AB = AC


⇒ ∠B = ∠C {angles opposite to equal sides are equal}


Also, sum of all the angles of a triangle is 180°.


⇒ ∠A + ∠B + ∠C = 180°


⇒ 2∠B = 180° - 80°


⇒ 2∠B = 100°


⇒ ∠B = ∠C = 50°

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5

An exterior angle of a triangle is 120° and one of the interior opposite angles is 30°. Find the other angles of the triangle.

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Fill up the blanks to make the following statements true:

(a) Sum of the angles of a triangle is _________


(b) An exterior angle of a triangle is equal to the sum of _________ opposite angles.


(c) An exterior angle of a triangle is always _________ than either of the interior opposite angles.


(d) A triangle cannot have more than _________ right angle.


(e) A triangle cannot have more than _______ obtuse angle.

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In right angled triangle, ∠A is right angle and ∠B = 35°, then ∠C is _______

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In a triangle ABC, ∠B = ∠C = 45°, then the triangle is ______