Uh this be confusing. The answer for C is 4.8 cm but how did this happen? See screenshot

Answer:
Heron's Formula
Step-by-step explanation:
We need to be able to get to the point where we have an Area so we can use the formula:
A = (1/2)(b)(h)
We are going to have to use Heron's Formula to Find the Height of the Triangle
To do this we are going to find the Semi-perimeter S = (a+b+c)/2:
S = (6+8+10)/2 = (24)/2 = 12
Then to find the area we can use the formula A = Sqrt[ S x (S-a) x (S-b) x (S-c)]:
A = sqrt[ 12 x (12-8) x (12-6) x (12-10)] = sqrt[ 12 x 4 x 6 x 2] = sqrt[576 ] = 24
So now we have have our original formula A = (1/2)(b)(h):
A = 24
b = 10
h = ?
24 = (1/2)(10)(h)
24 = 5h
h = 4.8