GCSE Secondary Maths Age 13-17 - Geometry & Measures: Polygons - Explained

The video tutorial explains how to solve a geometry problem involving a pentagon. It starts by identifying the problem and the need to calculate the size of a specific angle. The teacher explains the sum of angles in polygons, focusing on the pentagon's 540 degrees. Known angles are subtracted from this total to find the sum of two unknown angles. The relationship between these angles is given as a ratio, which is used to calculate the specific angle sizes. The tutorial concludes with a breakdown of how marks are awarded for each step in the solution process.

What is the total sum of interior angles in a pentagon?

• 360 degrees

• 180 degrees

• 540 degrees

• 720 degrees

If you know three angles in a pentagon are 125, 115, and 90 degrees, what is the sum of the remaining two angles?

• 150 degrees

• 240 degrees

• 210 degrees

• 180 degrees

How do you determine the relationship between angles B and C if angle C is twice angle B?

• By adding the angles

• By using a ratio of 2:1

• By subtracting the angles

• By dividing the angles

What is the size of angle C if the sum of angles B and C is 210 degrees and angle C is twice angle B?

• 105 degrees

• 70 degrees

• 210 degrees

• 140 degrees

What is the key value needed to solve the problem of finding angle B to C to D in the pentagon?

• The ratio of angles B and C

• The total degrees in a pentagon

• The sum of angles in a quadrilateral

• The sum of angles in a triangle