I am once again stuck on a question about geometry, this problem is about altitudes that crate right triangles:
Let there be a triangle that has side lengths of 13, 20, and 21. Given this, find the length of the altitude drawn to the side of length 21.
I have drawn the following picture to make my understanding clearer:
However, I am still not sure how to get the length of this altitude. My definition of an altitude is a segment drawn from one vertex to a point on the line opposite the point such that this segment is perpendicular to the line opposite the vertex.
I am very sure that to find the length, I will have to use the pythagorean theorem at some point, but I am not sure how to start this.
If anybody could give a starting point or hint that would be great :)
Note: I cannot use the cosine rule.
Thank you in advance.