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Trigonometry uses sine, cosine and tangent ratios to find missing sides and angles in right-angled triangles. Students go on to non-right-angled triangles using the sine rule, cosine rule, and area formula.
Students make these errors again and again. Knowing them in advance gives you a head start.
Mislabelling the sides (especially confusing adjacent and opposite)
Using the wrong trig ratio for the given sides
Forgetting to use the inverse trig function (sin⁻, cos⁻, tan⁻) when finding an angle
Insights pulled from Cambridge IGCSE (0580) examiner reports — the exact mistakes candidates make every year.
For similar shapes: area scale factor = (linear scale factor)², volume scale factor = (linear)³. If lengths are doubled, areas are × 4 and volumes are × 8 — not × 2.
Source: CIE 0580 · Feb/March 2024 · Paper 4 · Q2c(ii)
Circle theorem reasons must be exact: 'opposite ANGLES of a cyclic quadrilateral add to 180°' (not 'sides'). Use the precise syllabus vocabulary — 'linear pair' is NOT the CIE phrase.
Source: CIE 0580 · Feb/March 2024 · Paper 4 · Q2a
At each vertex of a polygon, interior angle + exterior angle = 180° (they form a straight line). It's the SUM of all exterior angles that equals 360°, not one pair.
Source: CIE 0580 · Feb/March 2023 · Paper 2 · Q12
Based on 3of 500+ insights extracted from CIE 0580 examiner reports (2018–2024).
This topic appears in the Cambridge IGCSE past papers. Our AI tutor can help with it on any question.
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Pythagoras' theorem relates the three sides of a right-angled triangle and is one of the most practical geometry topics at Cambridge IGCSE. It is used in 2D and 3D problems, coordinate geometry, and combined with trigonometry.
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