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Year 9 Trigonometry (Finding Sides) Worksheet — Level 3 — Practice Set 3 — Answers

Answer sheet with worked solutions for the Year 9 trigonometry worksheet.

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Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · Trigonometry

Year 9 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 side adjacent to a 38° angle is 16 m. Find the opposite side, to 1 decimal place.

Answer: 12.5 m

  1. tan 38° = opposite ÷ adjacent
  2. opposite = 16 × tan 38°
  3. ≈ 12.5
2.In a right-angled triangle, the side adjacent to a 69° angle is 24 m. Find the opposite side, to 1 decimal place.

Answer: 62.5 m

  1. tan 69° = opposite ÷ adjacent
  2. opposite = 24 × tan 69°
  3. ≈ 62.5
3.In a right-angled triangle, the hypotenuse is 25 cm and one angle is 34°. Find the side adjacent to the 34° angle, to 1 decimal place.

Answer: 20.7 cm

  1. cos 34° = adjacent ÷ hypotenuse
  2. adjacent = 25 × cos 34°
  3. ≈ 20.7
4.In a right-angled triangle, the hypotenuse is 26 cm and one angle is 30°. Find the side opposite the 30° angle, to 1 decimal place.

Answer: 13 cm

  1. sin 30° = opposite ÷ hypotenuse
  2. opposite = 26 × sin 30°
  3. ≈ 13
5.In a right-angled triangle, the hypotenuse is 18 cm and one angle is 64°. Find the side opposite the 64° angle, to 1 decimal place.

Answer: 16.2 cm

  1. sin 64° = opposite ÷ hypotenuse
  2. opposite = 18 × sin 64°
  3. ≈ 16.2
6.In a right-angled triangle, the hypotenuse is 26 cm and one angle is 42°. Find the side adjacent to the 42° angle, to 1 decimal place.

Answer: 19.3 cm

  1. cos 42° = adjacent ÷ hypotenuse
  2. adjacent = 26 × cos 42°
  3. ≈ 19.3
7.In a right-angled triangle, the hypotenuse is 20 cm and one angle is 26°. Find the side opposite the 26° angle, to 1 decimal place.

Answer: 8.8 cm

  1. sin 26° = opposite ÷ hypotenuse
  2. opposite = 20 × sin 26°
  3. ≈ 8.8
8.In a right-angled triangle, the side adjacent to a 39° angle is 12 m. Find the opposite side, to 1 decimal place.

Answer: 9.7 m

  1. tan 39° = opposite ÷ adjacent
  2. opposite = 12 × tan 39°
  3. ≈ 9.7
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