What is the length of the equilateral triangle below?

C. 5√3

Step-by-step explanation:

To figure this out, we need to apply the Pythagorean Theorem, a² + b² = c², where c is the "HYPOTENUSE". In this case, c is already found for us [10], so the operation we use whenever the hypotenuse is defined is deduction, or subtraction. Apply the Pythagorean Theorem: a² + 25 = 100; 75 = a². Now, to find a, we need to find two numbers that multiply to 75, where one of them is a PERFECT SQUARE, and in this case, they are 3 and 25. Since the square root of 25 is 5 [in this case, NO NON-NEGATIVE root], that gets moved to the outside of the radical, and 3 [NON-PERFECT SQUARE] stays wrapped under the radical, ending up with 5√3. You understand?

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72 is the answer to this problem