Math  /  Geometry

QuestionThe length of one leg of a right triangle is 7 cm more than that of the other leg. The length of the hypotenuse is 3 cm more than double that of the shorter leg. Find the lengths of each of the three sides.

Studdy Solution

STEP 1

1. Let the length of the shorter leg be x x cm.
2. The length of the longer leg is x+7 x + 7 cm.
3. The length of the hypotenuse is 2x+3 2x + 3 cm.
4. Use the Pythagorean theorem to relate the sides of the triangle.

STEP 2

1. Set up the equation using the Pythagorean theorem.
2. Solve the quadratic equation for x x .
3. Calculate the lengths of the legs and the hypotenuse.
4. Verify the solution.

STEP 3

Using the Pythagorean theorem, which states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides, set up the equation:
(x)2+(x+7)2=(2x+3)2 (x)^2 + (x + 7)^2 = (2x + 3)^2

STEP 4

Expand each term in the equation:
x2+(x+7)2=(2x+3)2 x^2 + (x + 7)^2 = (2x + 3)^2 x2+(x2+14x+49)=(4x2+12x+9) x^2 + (x^2 + 14x + 49) = (4x^2 + 12x + 9)

STEP 5

Combine like terms:
2x2+14x+49=4x2+12x+9 2x^2 + 14x + 49 = 4x^2 + 12x + 9

STEP 6

Rearrange the equation to bring all terms to one side:
0=4x2+12x+92x214x49 0 = 4x^2 + 12x + 9 - 2x^2 - 14x - 49 0=2x22x40 0 = 2x^2 - 2x - 40

STEP 7

Simplify the equation by dividing all terms by 2:
0=x2x20 0 = x^2 - x - 20

STEP 8

Solve the quadratic equation using the quadratic formula x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} , where a=1 a = 1 , b=1 b = -1 , and c=20 c = -20 :
x=(1)±(1)241(20)21 x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4 \cdot 1 \cdot (-20)}}{2 \cdot 1} x=1±1+802 x = \frac{1 \pm \sqrt{1 + 80}}{2} x=1±812 x = \frac{1 \pm \sqrt{81}}{2}

STEP 9

Calculate the roots:
x=1±92 x = \frac{1 \pm 9}{2}
This gives two possible solutions:
x=102=5 x = \frac{10}{2} = 5 x=82=4 x = \frac{-8}{2} = -4
Since a length cannot be negative, we take x=5 x = 5 .

STEP 10

Calculate the lengths of the other sides using x=5 x = 5 :
Shorter leg: x=5 x = 5 cm
Longer leg: x+7=5+7=12 x + 7 = 5 + 7 = 12 cm
Hypotenuse: 2x+3=2(5)+3=10+3=13 2x + 3 = 2(5) + 3 = 10 + 3 = 13 cm

STEP 11

Verify the solution by checking the Pythagorean theorem:
52+122=132 5^2 + 12^2 = 13^2 25+144=169 25 + 144 = 169 169=169 169 = 169
The solution satisfies the Pythagorean theorem.
The lengths of the sides of the triangle are:
Shorter leg: 5 5 cm
Longer leg: 12 12 cm
Hypotenuse: 13 13 cm

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