Junior Cycle · Trigonometry
⏱ Tested in 3 exam questions since 2023
Lesson 2 of 6
JCHL Trigonometry 2: SOHCAHTOA (Finding the Angle)
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- SOHCAHTOA: sin = opp/hyp, cos = adj/hyp, tan = opp/adj
- To find an ANGLE from two sides: write the ratio, then use sin⁻¹ / cos⁻¹ / tan⁻¹ (shift + sin/cos/tan)
- Make sure the calculator is in DEGREES (a little "D" at the top of the screen)
- sin A and cos A are always between −1 and 1; tan A is not bounded (it can be any value)
- Angle of elevation = looking UP from the horizontal; angle of depression = looking DOWN from the horizontal
Formula used
sin A = O/H, cos A = A/H, tan A = O/A
angle = sin⁻¹, cos⁻¹ or tan⁻¹ of the ratio
On page 16 of the log tables — read it off, don’t memorise.Most recent exam questions
- 2025 Q8(a)
- 2024 Q13(b)
- 2023 Q8(b)
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