Unit 6 · 3 lessons
Similar Triangles and Right-Triangle Trigonometry
Use ratio and proportion to work with similar triangles (shadows, mirrors, scale models, surveying), then build the sine, cosine and tangent ratios from similar right triangles and use them with the Pythagorean theorem to find unknown sides and angles in real situations.
- 36 practice questions
- 26 flashcards
- 1 interactive lesson
Lessons
- 1Similar TrianglesSimilar triangles have the same shape: their corresponding angles are equal and their corresponding sides are in proportion. Learn how to recognize them (AA, SSS and SAS similarity), how they differ from congruent triangles, and how to use them to measure things you cannot reach, such as the height of a tree from its shadow.12 questions
- 2The Primary Trigonometric RatiosEvery right triangle with the same acute angle has the same shape, so the ratios of its sides depend only on that angle. Those ratios are the sine, cosine and tangent. Learn to label the opposite, adjacent and hypotenuse sides, to use SOH CAH TOA to find a missing side, and to use the inverse ratios to find a missing angle.Interactive12 questions
- 3Solving Right-Triangle ProblemsPut the trigonometric ratios and the Pythagorean theorem to work on real measurements: heights you cannot reach, distances across water, directions for a boat, and the angle of a ladder or ramp. Learn angles of elevation and depression, how to solve a right triangle completely, and how to handle problems that need two right triangles.12 questions