Right Triangle Side Lengths: Solve for x+9, x+2, and x+10

Question

A right triangle is shown below.

x>1


Calculate the lengths of the sides of the triangle.

x+9x+9x+9x+2x+2x+2x+10x+10x+10

Video Solution

Solution Steps

00:00 Find the sides of the triangle
00:04 Use the Pythagorean theorem in the triangle to find X
00:12 Use the shortened multiplication formulas and open parentheses
00:27 Reduce what we can
00:36 Group like terms
00:50 Arrange the equation so that one side equals 0
01:05 Use the quadratic formula to find possible solutions
01:11 Find the numbers whose sum equals value B
01:17 And their product equals value C
01:25 These are the matching numbers
01:31 Substitute these numbers in the quadratic expression
01:36 Find when each factor in the multiplication equals zero
01:42 Isolate the unknown
01:45 We can see that this solution is not suitable due to the given domain
01:48 This is the possible solution for X
01:53 Substitute this solution in the side expressions to find the sides
02:00 And this is the solution to the problem

Step-by-Step Solution

To find the lengths of the sides of the right triangle, we will apply the Pythagorean theorem, which states a2+b2=c2a^2 + b^2 = c^2 for a right triangle, where cc is the hypotenuse.

Given the side lengths are x+9x + 9, x+2x + 2, and x+10x + 10, we assume x+10x + 10 is the hypotenuse because it is the largest value and confirm it by checking with the theorem.

Substitute into the Pythagorean theorem:
(x+2)2+(x+9)2=(x+10)2(x + 2)^2 + (x + 9)^2 = (x + 10)^2

Let's expand each side and solve for xx:
(x+2)2=x2+4x+4(x + 2)^2 = x^2 + 4x + 4
(x+9)2=x2+18x+81(x + 9)^2 = x^2 + 18x + 81
(x+10)2=x2+20x+100(x + 10)^2 = x^2 + 20x + 100

Combine these into a single equation:
x2+4x+4+x2+18x+81=x2+20x+100x^2 + 4x + 4 + x^2 + 18x + 81 = x^2 + 20x + 100

Simplify and combine like terms:
2x2+22x+85=x2+20x+1002x^2 + 22x + 85 = x^2 + 20x + 100

Rearrange to form a quadratic equation:
2x2+22x+85x220x100=02x^2 + 22x + 85 - x^2 - 20x - 100 = 0
x2+2x15=0x^2 + 2x - 15 = 0

Factor the quadratic equation:
(x+5)(x3)=0(x + 5)(x - 3) = 0

Solve for xx:
x+5=0x=5x + 5 = 0 \Rightarrow x = -5 (Not valid as x>1x > 1)
x3=0x=3x - 3 = 0 \Rightarrow x = 3

Therefore, substituting x=3x = 3 will provide the side lengths:
<begin><begin> - Short side: x+2=3+2=5x + 2 = 3 + 2 = 5
<sametime><same time> - Other side: x+9=3+9=12x + 9 = 3 + 9 = 12
<sell><sell> - Hypotenuse: x+10=3+10=13x + 10 = 3 + 10 = 13

These side lengths 55, 1212, and 1313 form a well-known Pythagorean triple. Therefore, the solution to the problem is 5,12,135, 12, 13.

Answer

5,12,13 5,12,13