In a right-angled triangle, one leg is 8 cm smaller than the other. Find the larger leg if the hypotenuse is 40 cm.
August 9, 2021 | education
| 1. A, B, C – the vertices of the triangle. ∠А = 90 °. BC = 40 cm.
2. AB is less than AC by 8 cm. AC = AB + 8 cm.
3. Take the length of the leg AB as x. AC leg = x + 8.
4. Let’s make the equation:
x² + (x + 8) ² = 40² (by the Pythagorean theorem).
x² + x² + 16x + 64 = 1600;
2x² + 16x – 1536 = 0;
x² + 8x – 768 = 0;
The first value x = (- 8 + √64 + 4 x 768) / 2 = (- 8 + √3136) / 2 = (- 8 + 56) / 2 = 24 cm.
The second value is x = (- 8 – 56) / 2 = – 32 cm. Not accepted.
AB = 24 cm.
AC = 24 + 8 = 32 cm.
Answer: AC = 32 cm – larger leg.
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