Let x=ab=ac, and y=bc, and z=ad.
Since the perimeter of the triangle abc is 36, you have:
Perimeter of abc = 36
ab + ac + bc = 36
x + x + y = 36
(eq. 1) 2x + y = 36
The triangle is isosceles (it has two sides with equal length: ab and ac). The line perpendicular to the third side (bc) from the opposite vertex (a), divides that third side into two equal halves: the point d is the middle point of bc. This is a property of isosceles triangles, which is easily shown by similarity.
Hence, we have that bd = dc = bc/2 = y/2 (remember we called bc = y).
The perimeter of the triangle abd is 30:
Permiter of abd = 30
ab + bd + ad = 30
x + y/2 + z =30
(eq. 2) 2x + y + 2z = 60
So, we have two equations on x, y and z:
(eq.1) 2x + y = 36
(eq.2) 2x + y + 2z = 60
Substitute 2x + y by 36 from (eq.1) in (eq.2):
(eq.2') 36 + 2z = 60
And solve for z:
36 + 2z = 60 => 2z = 60 - 36 => 2z = 24 => z = 12
The measure of ad is 12.
If you prefer a less algebraic reasoning:
- The perimeter of abd is half the perimeter of abc plus the length of ad (since you have "cut" the triangle abc in two halves to obtain the triangle abd).
- Then, ad is the difference between the perimeter of abd and half the perimeter of abc:
ad = 30 - (36/2) = 30 - 18 = 12
2x-4=3-x +1
<span>Simplifying
2x + -4 = 3 + -1x + 1
Reorder the terms:
-4 + 2x = 3 + -1x + 1
Reorder the terms:
-4 + 2x = 3 + 1 + -1x
Combine like terms: 3 + 1 = 4
-4 + 2x = 4 + -1x
Solving
-4 + 2x = 4 + -1x
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add 'x' to each side of the equation.
-4 + 2x + x = 4 + -1x + x
Combine like terms: 2x + x = 3x
-4 + 3x = 4 + -1x + x
Combine like terms: -1x + x = 0
-4 + 3x = 4 + 0
-4 + 3x = 4
Add '4' to each side of the equation.
-4 + 4 + 3x = 4 + 4
Combine like terms: -4 + 4 = 0
0 + 3x = 4 + 4
3x = 4 + 4
Combine like terms: 4 + 4 = 8
3x = 8
Divide each side by '3'.
x = 2.666666667
Simplifying
x = 2.666666667</span>
For the Fist One it’s Pentagonal Pyramid
Hello!
to solve this problem, use the following equation
<span><span><span>(<span>4/3(3.141593)</span>)</span>(9^</span>3) </span>= <span>3053.628059</span><span>
so your final answer is:
the volume of the volleyball is </span>3053.628059<span>
I hope this helps, and have a nice day.</span>
