Hi!
The equation to find the area of a triangle is...
(a = area
b = base
h = height)
![a = (1)/(2) bh](https://img.qammunity.org/2019/formulas/mathematics/college/9zwnktlpgk7flqk5z5rtfnirsi49eq055e.png)
Fill in the values that we already have.
Divide both sides by 1/2![861/ (1)/(2) = (1)/(2)/ (1)/(2)82*h](https://img.qammunity.org/2019/formulas/mathematics/college/cc4qe3e4fo0gutu32027ehso2lbhck8j5b.png)
1722 = 82*h
Divide both sides by 82.1722/82 = 82/82*h
21 = h
The answer is B. 21 cmHope this helps! :)