Year 11 Trigonometry (Finding Sides) Worksheet — Level 2 — Answers
Answer sheet with worked solutions for the Year 11 trigonometry worksheet.
Year 11 Trigonometry (Finding Sides) Worksheet — Level 2 — Answers
Label the sides (opposite, adjacent, hypotenuse), choose the ratio (SOH CAH TOA), then solve.
1.In a right-angled triangle, the side adjacent to a 36° angle is 11 m. Find the opposite side, to 1 decimal place.
Answer: 8 m
- tan 36° = opposite ÷ adjacent
- opposite = 11 × tan 36°
- ≈ 8
2.In a right-angled triangle, the side adjacent to a 53° angle is 16 m. Find the opposite side, to 1 decimal place.
Answer: 21.2 m
- tan 53° = opposite ÷ adjacent
- opposite = 16 × tan 53°
- ≈ 21.2
3.In a right-angled triangle, the hypotenuse is 21 cm and one angle is 54°. Find the side adjacent to the 54° angle, to 1 decimal place.
Answer: 12.3 cm
- cos 54° = adjacent ÷ hypotenuse
- adjacent = 21 × cos 54°
- ≈ 12.3
4.In a right-angled triangle, the hypotenuse is 27 cm and one angle is 24°. Find the side adjacent to the 24° angle, to 1 decimal place.
Answer: 24.7 cm
- cos 24° = adjacent ÷ hypotenuse
- adjacent = 27 × cos 24°
- ≈ 24.7
5.In a right-angled triangle, the hypotenuse is 10 cm and one angle is 33°. Find the side opposite the 33° angle, to 1 decimal place.
Answer: 5.4 cm
- sin 33° = opposite ÷ hypotenuse
- opposite = 10 × sin 33°
- ≈ 5.4
6.In a right-angled triangle, the hypotenuse is 16 cm and one angle is 44°. Find the side opposite the 44° angle, to 1 decimal place.
Answer: 11.1 cm
- sin 44° = opposite ÷ hypotenuse
- opposite = 16 × sin 44°
- ≈ 11.1
7.In a right-angled triangle, the side adjacent to a 55° angle is 14 m. Find the opposite side, to 1 decimal place.
Answer: 20 m
- tan 55° = opposite ÷ adjacent
- opposite = 14 × tan 55°
- ≈ 20
8.In a right-angled triangle, the hypotenuse is 29 cm and one angle is 61°. Find the side adjacent to the 61° angle, to 1 decimal place.
Answer: 14.1 cm
- cos 61° = adjacent ÷ hypotenuse
- adjacent = 29 × cos 61°
- ≈ 14.1
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.
Great work. Here's what to try next: