Use the Pythagoream theorem. Note that 20 is the longest side, and is c
a² = c² - b²
c = 20, b = 12, a = a
Plug in corresponding numbers to corresponding variables
a² = (20)² - (12)²
Simplify
a² = 400 - 144
Simplify. Combine like terms
a² = 256
Isolate the a. Root both sides
√a² = √256
a = √256
a = 16
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16 is your answer for a
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hope this helps
