Higher November 2017 Paper 4 Q7

OCRHigherCurrent spec5 marksAngles in Polygons

7 Angle BAE is part of a regular 18-sided polygon.
Angle CAD is part of a regular 10-sided polygon.
The dashed line through A is a line of symmetry of both polygons.

Point A with a horizontal dashed line through it; lines from A go up to B and C and down to E and D, with C and D outside B and E

Not to scale

Work out angle BAC. [5]

Mark scheme

Answer	Marks	Part marks and guidance
8	5	B3 for 20 and 36 M1 for (36 – 20) ÷ 2 OR M2 for 180 − (360 ÷18) soi by 160 or M1 for 360 ÷ 18 soi 20 and M2 for 180 − (360 ÷10) soi by 144 or M1 for 360 ÷ 10 soi 36	accept any correct method