You will only need to know the very basics of Trigonometry for the ISEE, and there may only be one or two questions concerning this branch of math. However, in order to answer these questions, you need to understand sine (sin), cosine (cos), tangent (tan), cosecant (csc), secant (sec), and cotangent (cot) in the context of right triangles. Two right triangles that have the same non‐right angles, such as two 45° – 45° – 90° triangles, will have proportional corresponding sides. For example, the ratio of one triangle’s hypotenuse to its height will be the same in the other triangle. These concepts represent these ratios.
You begin with a known non‐right angle, which is usually labeled as θ (theta). If both non‐right angles are known, then they might be labeled as α (alpha) and β (beta). From the known angle, you determine which leg is opposite from the angle and which leg is adjacent to the angle. The hypotenuse is always the slanted side.