O-LevelMathematicsGeometry4024/22 · Oct/Nov 2023 · Q28 Marks
Find the size of one interior angle of a regular 15-sided polygon.
- (a)(i)Find the size of one interior angle of a regular 15-sided polygon.[2]
- (a)(ii)The diagram shows part of a regular 15-sided polygon. Find the value of x.[2]
- (b)A, B, C and D are points on the circle, centre O. AB is a diameter of the circle. Angle BAC = 24°. Find angle ADC. Give a reason for each step of your working.[4]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.
- [2] M1 for [180 - 360/15] oe or 180(15-2) [/15] oe
- [2] M1 for 180 - their156 oe soi where 90 < their 156 < 180
- [4] B2 for ∠ADC = 114 nfww
- or B1 for ∠ACB = 90 or ∠ABC = 66 or ∠ADB = 90 or ∠BDC = 24
- AND
- B2 for complete reasons for a correct method to find ∠ADC
- or B1 for reason 'angle in semicircle' or '[angles in] opposite segments [are supplementary]' or '[angles in] same segment [are equal]' correctly linked with the appropriate angles
- Max 3 marks if any incorrect angles or reasons
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →