Trigonometry links angles and sides in right-angled triangles. In this topic you will learn sin, cos, tan, how to use them to find sides and angles, and how to solve problems including angles of elevation and depression. O-Level only.
Labelling the triangleFor angle θ:Opposite = side opposite θAdjacent = side next to θ, not hypotenuseHypotenuse = longest sideRatiossin θ …
View LessonMethod1. Label Opp, Adj, Hyp for the given angle.2. Choose sin, cos or tan depending on which two sides you …
View LessonMethod1. Label sides.2. Choose sin, cos or tan.3. Use inverse: sin-1, cos-1, tan-1.Example: Opp = 7 cm, Hyp = 10 …
View LessonDefinitionsAngle of elevation: Angle measured upwards from the horizontal to a point above.Angle of depression: Angle measured downwards from the …
View LessonIn right-angled triangle ABC, ∠C = 90°. Find the value:sin A if opposite = 3, hypotenuse = 5cos A if …
View Exercise Submit ExerciseFind x to 3 s.f. Diagrams are right-angled.Angle 40°, adjacent = 15 cm, opposite = xAngle 25°, hypotenuse = 20 …
View Exercise Submit ExerciseFind θ to 1 d.p.Opposite = 4 cm, hypotenuse = 9 cmAdjacent = 6 cm, hypotenuse = 8 cmOpposite = …
View Exercise Submit ExerciseDraw a diagram and solve:From a point 80 m from a building, the angle of elevation to the top is …
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