Category Archives: MTH 201

Move on to non-right triangles

Move on to non-right triangles.. Because non-right triangles do not have a right angle (that’s kind of the definition), the three trigonometric ratios play a smaller role here (although they can also be used in some situations). Rather, two other rules become very important: The Sine Rule, and The Cosine Rule. The following articles explain these rules in detail.

Start with studying right-angled triangles.

Start with studying right-angled triangles. Right angled triangles are easy to study and will give you a good grasp of basic trigonometry and the three trigonometric ratios.

  • Familiarize yourself with the three sides of a right-angled triangle.
    1. The hypotenuse is the side opposite the right angle. It is the biggest side of any right triangle.
    2. The two other sides are called the legs of the triangle. If you pick any angle in the triangle (besides the right angle), you will see that one leg is adjacent to the angle, and the other leg is opposite the angle.
  • Familiarize yourself with the three trigonometric ratios, the base of trigonometry:
    1. The Sine of any angle is the ratio of the length of the side opposite it to the length of the hypotenuse.
    2. The Cosine of any angle is the ratio of the length of the side adjacent to it to the length of the hypotenuse.
    3. The Tangent of any angle is the ratio of the Sine of the angle to the Cosine of the angle. It is often also taken as the ratio of the opposite to the adjacent. The first definition is especially of help in solving trigonometric equations and proving identities while the second is sufficient for a basic study of trigonometry.