A collection of three worksheets:* An introductory worksheet on the trigonometric ratios sine, cosine and tangent. The exercises require to evaluate these ratios for an angle in a given triangle, to identify the trigonometric ratio that corresponds to a given ratio for a given triangle, to use a calculator to evaluate the trigonometric ratio of a given angle or the angle given one of its trigonometric ratios and to associate the sine or cosine of an angle to the cosine or sine of its complementa