Question

Find Q12 ...............

Answer 1

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Here is the solution:

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It is a regular polygon:

=> all interior angles are equal

AB, BC and CD are consecutive sides:

=> ΔABC is an isosceles triangle

Find one interior angle:

Sum of angles = 180

∠ABC = 180 - 20 - 20 = 140°

Find one exterior angle:

Exterior angle = 180 - interior angle

Exterior angle = 180 - 140 = 40°

Find number of sides:

Sum of all exterior angles = 360

Number of sides = 360 ÷ one exterior angle

Number of sides = 360 ÷ 40

Number of sides = 9

Answer: (a) 40°, (b) 140°, (c) 9 sides