Given ABC with vertices A(0, 8), B(3, 0) and C(-3, 0). Find the length of the altitude from A. (This is the second part of the question. The first part was to show that ABC was isosceles, which I did. But I am not sure how to solve this.)
FYI (AC=AB=the root of 73 and BC=6)
But how do I find this question.

Question

Given ABC with vertices A(0, 8), B(3, 0) and C(-3, 0). Find the length of the altitude from A. (This is the second part of the question. The first part was to show that ABC was isosceles, which I did. But I am not sure how to solve this.) 
FYI (AC=AB=the root of 73 and BC=6)
But how do I find this question.

anonymous · Answer

The box, next to ABC, means triangle. Sorry about the confusion...

wolf1728 · Answer

From the graph it is easy to see that the height of altitude AD is 8.  
But if you want to solve this mathematically then
Altitude AD² = AB² - DB²
Altitude AD² = 73 - 9
Altitude AD = sqrt(64)
Altitude AD = 8

anonymous · Answer

Thank you!

anonymous · Answer

But where does D come from?

wolf1728 · Answer

I just entered the letter 'D' as the midpoint of line CB.
I thought it showed the Pythagorean Theorem calculations more clearly.