Question

A right-angled triangle has sides of lengths (x+5)cm, (x-3)cm and 9cm. Calculate the value of x

Answer 1

x=4.0625 cm

Explanation:

The Pythagorean theorem states that the square of the hypotenuse of a right triangle equals the sum of the squares of the two legs.

Not knowing which is the hypotenuse, lets assume that (x+5)cm is the hypotenuse:

(x+5)^2= 9^2+(x-3)^2

(x^2+10x+25)=81+(x^2-6x+9)

x^2+10x+25=81+x^2-6x+9

16x=65

x=4.0625

Checking:

(4.0625+5)^2=9^2+(4.0625-3)^2

82.1289=82.1289

Answer 2

x = (3.95 and -5.95)

Explanation:

Given:

Hypotenuse = 9 cm

Perpendicular = (x+5) cm

Base = (x-3) cm

Find:

Value of x

Computation:

Using Pythagoras theorem

Hypotenuse² = Perpendicular² + Base²

9² = (x+5)² + (x-3)²

81 = x² + 25 + 10x + x² + 9 - 6x

2x² + 4x - 47 = 0

Quadratic Formula

x = [-b±√b²-4ac] / 2a

x = [-4±√16+376] / 2(2)

x = (3.95 and -5.95)