This week I have learned about trigonometry, which is to find angles or length of triangles and there are three ratios such as the sine ratio, cosine ratio, and tangent ratio.  This method can be only used to triangles that have 90 degrees. when we saw a right- angle triangle, the first thing to do is to label the sides of it. each side has its name, for example, the longest side we will call it hypotenuse, which is always opposite to the right- angle, then the other two sides are either the opposite side of the adjacent, it will depend on which angle the question gave. If there are no other angels given or length except the 90 degrees angle, then the trigonometric ratios could not be calculated.