Geometry Notes Lesson 5.3A – Trigonometry T.2.G.6 Use trigonometric ratios (sine, cosine, tangent) to determine lengths of sides and measures of angles in right triangles including angles of elevation and angles of depression T.2.G.7 Use similarity of right triangles to express the sine, cosine, and tangent of an angle in a right triangle as a ratio of given lengths of sides

Vocabulary Trigonometry –Triangle Measurement

Trigonometric Ratios sine = cosine = tangent = A B C c b a

sin A = sin B = cos A = cos B = tan A = tan B = A B C c b a

Example 1 Find the sine, cosine, and tangent of A and B. sin A = sin B = cos A = cos B = tan A = tan B = A B C 5 4 3

Writing Trig Ratios θ Using the ___________________, find the missing side. Pythagorean Theorem 2. Label each side according to the angle θ. 3. Write the ratio for sine, cosine, and tangent.