Question

The sides of a right angled triangle has sides (x+1)cm, (x+2)cm and (x+4) cm.
i) Find the area of the triangle
ii) find the perimeter of the triangle
pls someone answer this. question ASAP. TNX ​

Answer 1

Step-by-step explanation:

right-angled triangle.

that means Pythagoras applies :

c² = a² + b²

c being the Hypotenuse (the side opposite of the 90° angle and the longest of the 3 sides).

(x+4)² = (x+1)² + (x+2)²

x² + 8x + 16 = x² + 2x + 1 + x² + 4x + 4

8x + 16 = x² + 6x + 5

x² - 2x = 11

remember,

(x-a)² = x² -2ax + a²

compare to what we have

-2a = -2

a = 1

so, the full square on the left side is

(x-1)² = x² - 2x + 1

to complete the square in our equation we need to add 25 on both sides

x² - 2x + 1 = 11 + 1 = 12

(x - 1)² = 12

x - 1 = sqrt(12)

x = sqrt(12) + 1

and so

i)

when we have all 3 sides a, b, c, the area of the triangle is according to Heron's formula

S = (a + b + c)/2

Area = sqrt(S(S-a)(S-b)(S-c))

in our case that is

S = ((x+1) + (x+2) + (x+4))/2 =

= ((sqrt(12)+1+1) + (sqrt(12)+1+2) + (sqrt(12)+1+4))

/2 = (3×sqrt(12) + 10)/2 =

= 10.19615242...

Area = sqrt(S(S- sqrt(12)-2)(S-sqrt(12)-3)(S-sqrt(12)-5)) =

= sqrt(10.19615242... ×

4.732050808... ×

3.732050808... ×

1.732050808...) =

= sqrt(311.8845727...) =

= 17.66025404... cm²

ii)

the perimeter is

(sqrt(12)+1+1) + (sqrt(12)+1+2) + (sqrt(12)+1+4) =

3sqrt(12) + 10 = 20.39230485... cm

Answer 2

Answer:

i)  (9 + 5√3)  cm²

ii)  (10 + 6√3)  cm

Step-by-step explanation:

Given sides of a right triangle:

• (x + 1) cm
• (x + 2) cm
• (x + 4) cm

The longest side of a right triangle is the hypotenuse.

The two shortest sides of a right triangle are the legs.

To find the value of x use Pythagoras Theorem.

Pythagoras Theorem

$a^2+b^2=c^2$

where:

• a and b are the legs of the right triangle.
• c is the hypotenuse (longest side) of the right triangle.

Substitute the given expressions for the legs and hypotenuse into the formula:

$\begin{aligned}a^2+b^2 & =c^2\\\implies (x+1)^2+(x+2)^2 & =(x+4)^2\\(x+1)(x+1)+(x+2)(x+2) & =(x+4)(x+4)\\x^2+2x+1+x^2+4x+4 & =x^2+8x+16\\2x^2+6x+5 & =x^2+8x+16\\2x^2-x^2+6x-8x+5-16 & =0\\x^2-2x-11 & =0\end{aligned}$

To find the value of x use the quadratic formula.

Quadratic Formula

$x=\dfrac{-b \pm \sqrt{b^2-4ac} }{2a}\quad\textsf{when }\:ax^2+bx+c=0$

$\implies a=1,\quad b=-2, \quad c=-11$

Therefore:

$\implies x=\dfrac{-(-2) \pm \sqrt{(-2)^2-4(1)(-11)} }{2(1)}$

$\implies x=\dfrac{2 \pm \sqrt{4+44}}{2}$

$\implies x=\dfrac{2 \pm \sqrt{48}}{2}$

$\implies x=\dfrac{2 \pm \sqrt{16 \cdot 3}}{2}$

$\implies x=\dfrac{2 \pm \sqrt{16}\sqrt{3}}{2}$

$\implies x=\dfrac{2 \pm 4\sqrt{3}}{2}$

$\implies x=1 \pm 2\sqrt{3}$

As  1 - 2√3 ≈ -2.46  we can discount this value of x as it would make two of the sides of the triangle negative values.  Since length cannot be negative, the only valid value of x is 1 + 2√3.

Therefore the lengths of the sides of the right triangle are:

• (1 + 2√3 + 1) = (2 + 2√3) cm
• (1 + 2√3 + 2) = (3 + 2√3) cm
• (1 + 2√3 + 4) = (5 + 2√3) cm

Part (i)

Area of a triangle

$\sf Area = \dfrac{1}{2}bh$

where:

• b = base
• h = height

The base and the height of a right triangle are its legs.

Substitute the found length of the legs into the formula and solve:

$\begin{aligned}\sf Area & = \sf \dfrac{1}{2}bh\\\\\implies \sf Area & = \dfrac{1}{2}(2+2\sqrt{3})(3+2\sqrt{3})\\\\& = \dfrac{1}{2}(6+10\sqrt{3}+12)\\\\ & = \dfrac{1}{2}(18+10\sqrt{3})\\\\ & = 9+5\sqrt{3} \:\:\sf cm^2\end{aligned}$

Part (ii)

The perimeter of a two-dimensional shape is the distance all the way around the outside. Therefore, the perimeter of a triangle is the sum of the lengths of its sides.

$\begin{aligned}\sf Perimeter & = (2+2\sqrt{3})+(3+2\sqrt{3})+(5+2\sqrt{3})\\& = 2+3+5+2\sqrt{3}+2\sqrt{3}+2\sqrt{3}\\& = 10+6\sqrt{3}\:\: \sf cm\end{aligned}$