Answer:
-You should already be familiar with algebra and geometry before learning trigonometry. From algebra, you should be comfortable with manipulating algebraic expressions and solving equations. From geometry, you should know about similar triangles, the Pythagorean theorem, and a few other things, but not a great deal.
-Measure the lengths of the sides of sets of similar right angled triangles and find the ratio of sides.
-Investigate the relationship between these ratios and the angle size.
-Use calculators or tables to find the sine, cosine and tangent of angles.
Explanation:
basic knowledge i guess