MYP Maths Trigonometry (SOHCAHTOA): Common Questions Answered

Trigonometry is hard because it's the first topic where you must decide which method to use before calculating — unlike Pythagoras, where there's only one formula. Students who've relied on memorising steps struggle because SOHCAHTOA needs you to identify the right sides and angle first.

SOHCAHTOA is a memory device for the three trig ratios in a right-angled triangle: Sine = Opposite/Hypotenuse, Cosine = Adjacent/Hypotenuse, Tangent = Opposite/Adjacent. You use it to find a missing side or angle once you've labelled the triangle relative to a known angle.

Sine, cosine and tangent are just different ratios of the same right-angled triangle's sides, each linked to a specific angle. Sine compares opposite to hypotenuse, cosine compares adjacent to hypotenuse, and tangent compares opposite to adjacent — no hypotenuse involved at all.

Identify which angle you're working from, label the three sides relative to that angle, then check which two sides the question involves — the known one and the one you're solving for. Whichever ratio pairs those two sides is the one you use.

Level 7 work under Criterion A and D isn't about harder arithmetic — it's about justifying your method and applying trig to unfamiliar, real-world contexts (angles of elevation, bearings, 3D shapes). Show your reasoning at every step, not just the final rounded answer.

The top mistake is mislabelling opposite and adjacent relative to the wrong angle, especially when the triangle is drawn at an angle on the page. Second most common: using degrees mode instead of radians (or vice versa) on the calculator without checking.

Yes — MYP 4-5 trigonometry questions generally expect a graphic display calculator (GDC) to find sine, cosine and tangent values, since these aren't whole numbers for most angles. Make sure it's set to degree mode, not radians, before every trig question.

Trigonometry is typically assessed under Criterion A (Knowing and Understanding) for applying SOHCAHTOA correctly, and Criterion D (Applying Mathematics in Real-World Contexts) when questions involve elevation, bearings or navigation problems. Some schools also assess reasoning under Criterion B.

MYP 4-5 trigonometry centres on right-angled triangles using SOHCAHTOA, plus applied problems like angles of elevation/depression and bearings. Extended or higher-level MYP 5 classes may preview the Sine Rule and Cosine Rule for non-right-angled triangles ahead of DP Maths.

Most schools introduce SOHCAHTOA in MYP 4, building on Pythagoras' Theorem from MYP 3, then extend it with applied problems and 3D trigonometry through MYP 5. Exact timing varies by school since the IB sets broad content, not a fixed year-by-year sequence.

No — MYP trigonometry covers right-angled triangles with SOHCAHTOA and basic applications. DP Mathematics (both Analysis and Approaches and Applications and Interpretation, first examined 2021) goes much further: the Sine and Cosine Rules, radians, trig identities, and trig functions as graphs.

MYP and GCSE trigonometry cover almost identical ground at this stage — SOHCAHTOA, right-angled triangles, angles of elevation and depression. The main difference is assessment style: MYP grades via criteria-based rubrics (A–D) rather than GCSE's mark-scheme-driven exam papers.

You don't need to re-learn the maths — the most useful thing you can do is ask your child to explain which ratio they've chosen and why, before they calculate anything. If they can't explain it, that's the gap to work on, not the arithmetic.