Higher June 2019 Paper 4 Q9

OCRHigherCurrent spec5 marksAngles (Including Parallel Lines)

9 The diagram shows triangle ABC.
CD is parallel to AB.
A, C and E lie in a straight line.
Angles of size \(a\)°, \(b\)° and \(c\)° are shown.

Triangle ABC with base AC extended to E; CD is parallel to AB; angle a° at A, angle b° at B and angle c° at C inside the triangle

Not to scale

(a) Insert \(a\)°, \(b\)° or \(c\)° to make this statement true.
Give a reason for your answer.

Angle DCE = ......... because ...... [2]

(b) Use the diagram and the answer to part (a) to show that the angles of a triangle add up to 180°.
Give a reason for each statement you make. [3]

Mark scheme (a)

Answer	Marks	Part marks and guidance
\(a\), A, [angle] BAC or [angle] CAB corresponding	1 1	not numbers Condone misspellings e.g. correspondent but not F angles. Any longer reasons must be correct and complete.