Finding the Size of an Angle in a Polygon

The video tutorial explains how to calculate the size of angle X in a geometric diagram featuring a regular pentagon, a regular octagon, and an isosceles triangle. It covers the method to calculate interior angles of polygons using a specific formula, marking these angles on a diagram, and then using this information to find angle X. The tutorial also reviews the solution and discusses the allocation of marks for each step.

What is the significance of marking equal sides in the diagram?

• To identify the type of polygons

• To ensure accurate angle calculations

• To determine the perimeter of the shapes

• To find the area of the polygons

How do you calculate the interior angle of a regular pentagon?

• Divide the total degrees by the number of sides

• Subtract 2 from the number of sides and multiply by 180

• Multiply the number of sides by 180

• Add 2 to the number of sides and multiply by 180

What is the interior angle of a regular pentagon?

• 90 degrees

• 108 degrees

• 120 degrees

• 135 degrees

What is the formula used to calculate the interior angle of a regular octagon?

• N subtract 2, multiplied by 180

• N add 2, multiplied by 180

• N subtract 1, multiplied by 180

• N add 1, multiplied by 180

What is the interior angle of a regular octagon?

• 150 degrees

• 108 degrees

• 120 degrees

• 135 degrees

How do you find the angle at point B in the isosceles triangle?

• Multiply the angles of the pentagon and octagon

• Divide the angles of the pentagon and octagon

• Subtract the angles of the pentagon and octagon from 360

• Add the angles of the pentagon and octagon

What is the final value of angle X in the isosceles triangle?

• 31.5 degrees

• 45 degrees

• 90 degrees

• 60 degrees