One of the legs of a right-angled triangle is 2 cm less than the second and the perimeter is 34 cm, find the area of the triangle.
February 25, 2021 | education
| 1. Length of the first leg: A cm;
2. Length of the second leg: B cm;
3. Length of the hypotenuse: C cm;
4. By the condition of the problem:
A = B + 2;
A + B + C = 34 cm;
5. Hypotenuse:
C = 34 – (A + B) = 34 – (B + 2 + B) = 32 – 2 * B;
6. Pythagoras to help us:
A² + B² = C²;
(B + 2) ² + B² = (32 – 2 * B) ²;
2 * B² + 4 * B + 4 = 1024 – 128 * B + 4 * B²;
B² – 66 * B + 510 = 0;
B1,2 = 33 + – sqrt (33² -510) = 33 + – 24;
B1 = 33 + 24 = 57, (will not work, more than the perimeter);
B = 33 – 24 = 9 cm;
A = B + 2 = 9 + 2 = 11 cm;
7. Area of the triangle: S cm²;
S = (A * B) / 2 = (11 * 9) / 2 = 49.5 cm².
Answer: S = 49.5 cm².
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