The exercise is solved by applying the Pythagorean Theorem:
h^2= a^2 + b^2
h= √(a^2 + b^2)
h: hypotenuse (the opposite side of the right angle and the longest side
of the triangle).
a and b: legs (the sides that form the right angle).
The first objective will be to find the value of AD:
AD= AB - DB
We don't know the DB leg, so we proceed to find it clearing it from the
Pythagorean equation:
h^2= a^2 + b^2
a= √ (h^2 - b^2)
a= √ (17^2 - 8^2)
a= DB= 15
Then, AD is:
AD= 21-15= 6
Once we find the value of the AD leg, we can find the hypotenuse AC:
h= √ (a^2 + b^2)
h= √ (6^2 + 8^2)
h= AC= 10
The answer is: C. 10
