Angle sum: Angles in a triangle add to 180°.
Exterior angle: Exterior angle = sum of two opposite interior angles.
Isosceles triangle: Base angles are equal.
Equilateral triangle: All angles 60°.
Sum of interior angles = (n-2) × 180°, where n = number of sides.
Each interior angle of regular polygon = [(n-2) × 180°] ÷ n
Sum of exterior angles of any polygon = 360°.
Each exterior angle of regular polygon = 360° ÷ n
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Calculate:A triangle has angles 50°, 60°. Find the third angle.In isosceles triangle ABC, AB=AC and ∠BAC = 40°. Find ∠ABC.Sum …
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