Hint
Use the stated units and precision. Use equal perpendicular distances on opposite sides of the vertical mirror.
Worked solution
(a)
Use equal perpendicular distances on opposite sides of the vertical mirror.
The mirror bisects the horizontal segment, so \(\displaystyle x'=2k-x=-9\).
Answer: \(-9\)
(b)
Preserve the coordinate parallel to the vertical mirror.
A vertical mirror leaves the y-coordinate unchanged at 4.
Answer: \(4\)
(c)
Preserve the coordinate parallel to the horizontal mirror.
A horizontal mirror leaves the x-coordinate unchanged at 7.
Answer: \(7\)
Maths4U indicative marking guidance
Maths4U indicative marking guidance, not an official mark scheme. Credit complete valid alternative methods and consequential reasoning. An unexplained result does not earn a method mark.
(a) · 2 marks
- 1 mark: Use equal perpendicular distances on opposite sides of the vertical mirror.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Keep intermediate values exact until the final step.
(b) · 2 marks
- 1 mark: Preserve the coordinate parallel to the vertical mirror.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Check the answer against the original conditions.
(c) · 2 marks
- 1 mark: Preserve the coordinate parallel to the horizontal mirror.
- 1 mark: Give the correct requested result, retaining signs, units and any domain restrictions.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Keep intermediate values exact until the final step.
Total: 6 marks.