Shape and Space 5

3 marks · Normal

Triangle P is translated and then reflected.

Triangle P with vertices A(1, 1), B(4, 1) and C(1, 4) is translated by the vector , then reflected in the line . Give the coordinates of the vertices after both transformations. Show all your working.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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A'(–1, 3), B'(–4, 3), C'(–1, 6)

Also accept: Written as table or list, order of points unimportant

Common mistakes: Reflecting before translating

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Correct translation of all three vertex coordinates. (follow-through)

M2 · 1 mark · Correct method for reflecting a point in the line . (follow-through)

A1 · 1 mark · All final coordinates correct after both transformations. (follow-through)

Worked solution

Step 1: Translate each point by :

Translated vertices
Point	Original	Translated
A	(1, 1)	(4, 3)
B	(4, 1)	(7, 3)
C	(1, 4)	(4, 6)

Step 2: Reflect in (the x-coordinate of each point becomes ):

Reflected vertices
Point	Translated	Reflected
A'	(4, 3)	(–1, 3)
B'	(7, 3)	(–4, 3)
C'	(4, 6)	(–1, 6)