O-LevelMathematicsGeometry4024/12 · May/June 2017 · Q194 Marks
A pentagon has four angles of 2x° and one angle of x°. Calculate the value of x.
- (a)A pentagon has four angles of 2x° and one angle of x°. Calculate the value of x.[2]
- (b)ABCD and EBCF are parts of two identical regular n-sided polygons. [Figure: Diagram showing two polygons joined along edge BC. Angle DCF = 30° is marked.] The two polygons are joined together along edge BC. Angle DCF = 30°. Calculate the value of n.[2]
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 (May/June 2017). The mark or mark type is shown in brackets.
- [2] (a) 60
- B1 for [angle sum of pentagon = ] 540 or (5-2) × 180 oe
- [2] (b) 24 nfww
- B1 for exterior angle = 15° or interior angle = 165° soi
- or M1 for (360-30)/2 or (180(n-2))/n oe
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