The hypotenuse of a right-angled triangle is 10 centimeters. Find his legs if their sum is 14 centimeters.
April 28, 2021 | education
| 1) Let x cm be the length of one leg, then (14 – x) cm is the length of the second leg.
2) By the Pythagorean theorem, the sum of the squares of the legs is equal to the square of the hypotenuse:
x ^ 2 + (14 – x) ^ 2 = 10 ^ 2.
3) Solve the equation:
x ^ 2 + 196 – 28x + x ^ 2 = 100;
2x ^ 2 – 28x + 96 = 0;
x ^ 2 – 14x + 48 = 0.
By Vieta’s theorem:
x1 + x2 = 14;
x1 * x2 = 48, where x1 and x2 are the roots of the equation x ^ 2 – 14x + 48 = 0.
We select and get: x1 = 6, x2 = 8.
4) One leg of the triangle is either 6 cm or 8 cm.
5) Then the second leg:
14 – 6 = 8 cm
or 14 – 8 = 6 cm.
Answer: 6 and 8 cm.
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