Brainlag PlusFind an angle with sin⁻¹, cos⁻¹ or tan⁻¹, and use trigonometry for angles of elevation and depression and for bearings.
Undo the ratio
To find an angle, work out the ratio from the two sides, then use the inverse: sin⁻¹, cos⁻¹ or tan⁻¹ (SHIFT then sin on most calculators).
- opposite 7 cm, hypotenuse 12 cm
- sin θ = 7/12
- θ = sin⁻¹(7/12) = 35.68... = 35.7° (1 d.p.)
Keep the whole fraction in the calculator: rounding 7/12 to 0.58 first gives 35.5°, which is wrong to 1 d.p.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 4, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- The Scientific Calculator beside every question
- Anything you get wrong is saved to your flashcards