Maths: Applications and Interpretation · Geometry and trigonometry. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Test this topic freeAll Maths: Applications and Interpretation topics
Trigonometry links the sides and angles of a triangle. In a right-angled triangle, name the sides from the angle you are using: opposite, adjacent and hypotenuse. Then pick the ratio (sine, cosine or tangent) that contains the two sides in the question.
When the triangle has no right angle, use the sine rule or the cosine rule. Use the sine rule when you know a side and the angle opposite it. Use the cosine rule when you know two sides and the angle between them, or all three sides.
In every formula, side a is opposite angle A, side b is opposite angle B and side c is opposite angle C.
In the cosine rule students work out (a2 + b2 − 2ab) and then multiply by cos C. Multiply 2ab by cos C first, then subtract. Also check the calculator is in degree mode.
Answer: Third side 8.72 cm; area 26.0 cm2 (3 significant figures)
Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.
← Three-dimensional geometry: distance, solids and anglesApplications of trigonometry: elevation, bearings, arcs and sectors →Take a Maths: Applications and Interpretation test