Question

Find the coordinates of M' after a reflection across the line y= -1 and then across the x=-2.

Answer 1

M' = (-1, 3)

Explanation:

The two reflections are equivalent to a reflection across the point P = (-2, -1), which becomes the midpoint of the line segment MM'. The coordinates of M' can be found from ...

M' = 2P -M = 2(-2, -1) -(-3, -5) = (-4+3, -2+5)

M' = (-1, 3)

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The formula used comes from the formula for the midpoint:

P = (M +M')/2

2P = M + M' . . . . multiply by 2

M' = 2P - M . . . . .subtract M