Year 11 Trigonometry (Finding Sides) Worksheet — Level 3 — Practice Set 3 — Answers
Answer sheet with worked solutions for the Year 11 trigonometry worksheet.
Year 11 Trigonometry (Finding Sides) Worksheet — Level 3 — Practice Set 3 — Answers
Label the sides (opposite, adjacent, hypotenuse), choose the ratio (SOH CAH TOA), then solve.
1.In a right-angled triangle, the hypotenuse is 26 cm and one angle is 43°. Find the side opposite the 43° angle, to 1 decimal place.
Answer: 17.7 cm
- sin 43° = opposite ÷ hypotenuse
- opposite = 26 × sin 43°
- ≈ 17.7
2.In a right-angled triangle, the side adjacent to a 62° angle is 8 m. Find the opposite side, to 1 decimal place.
Answer: 15 m
- tan 62° = opposite ÷ adjacent
- opposite = 8 × tan 62°
- ≈ 15
3.In a right-angled triangle, the side adjacent to a 58° angle is 9 m. Find the opposite side, to 1 decimal place.
Answer: 14.4 m
- tan 58° = opposite ÷ adjacent
- opposite = 9 × tan 58°
- ≈ 14.4
4.In a right-angled triangle, the side adjacent to a 45° angle is 13 m. Find the opposite side, to 1 decimal place.
Answer: 13 m
- tan 45° = opposite ÷ adjacent
- opposite = 13 × tan 45°
- ≈ 13
5.In a right-angled triangle, the hypotenuse is 30 cm and one angle is 37°. Find the side adjacent to the 37° angle, to 1 decimal place.
Answer: 24 cm
- cos 37° = adjacent ÷ hypotenuse
- adjacent = 30 × cos 37°
- ≈ 24
6.In a right-angled triangle, the hypotenuse is 10 cm and one angle is 25°. Find the side opposite the 25° angle, to 1 decimal place.
Answer: 4.2 cm
- sin 25° = opposite ÷ hypotenuse
- opposite = 10 × sin 25°
- ≈ 4.2
7.In a right-angled triangle, the hypotenuse is 25 cm and one angle is 56°. Find the side adjacent to the 56° angle, to 1 decimal place.
Answer: 14 cm
- cos 56° = adjacent ÷ hypotenuse
- adjacent = 25 × cos 56°
- ≈ 14
8.In a right-angled triangle, the side adjacent to a 52° angle is 17 m. Find the opposite side, to 1 decimal place.
Answer: 21.8 m
- tan 52° = opposite ÷ adjacent
- opposite = 17 × tan 52°
- ≈ 21.8
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
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