How To Find the Cubic Feet of a Triangle

Mathematics is fun for some and a big burden for others. Some students are quite helpless at math and wish for the subject to be removed from the curriculum. Alas, that cannot be so since math is actually part of every day life. Geometry is a branch of mathematics that deals with the properties of different shapes such as circles, squares and triangles. With a simple mathematical formula, it is possible to find the cubic feet of a triangle. You will find the instructions below.

  • A right triangle is one half of a rectangle so it is easy to find its cubic feet. The formula for getting the cubic feet of a rectangle is to multiply the width of the rectangle by its length, usually represented by a x b = size in square feet. Since a right triangle is half of a rectangle, the formula to get the cubic feet of a right triangle is to multiply a x b as in the formula for the rectangle and divide it by 2 since the right triangle is half of the rectangle.
  • Let us say that you have a scalene triangle wall which has no equal sides and no equal angles and you need to calculate how many square feet it will be, given that the wall will be ten feet high. The formula for this is as follows:

        Area  = perimeter size x wall height

        Given: Triangle sides: a = 18 feet; b = 26 feet; and c = 32 feet.
                    Wall height = 10 feet

Add the three numbers together to get the perimeter size as follows: 18 feet + 26 feet + 32 feet = 76 feet.

Knowing that the formula is perimeter size x wall height, you can factor in the known variables to give you: 76 feet x 10 feet = 710 square feet

  • If you are given a problem where not all the variables are given, it is still possible to solve the problem by looking for the unknown variable first. You were given a triangle where the lengths of the two sides are not known. Looking at the triangle you noticed that if you draw a straight line from the apex to the base of the triangle you would be able to get two right triangles. When you do this, you will find it easier to solve the problem. You still do not know the size of the two areas of the triangle called the hypotenuses but you know that the height is 14 feet and the base has a total of twenty feet which when split into two gives a base of 12 feet for the larger triangle and 8 feet for the smaller triangle. To write the formula you have to name the sides of the triangles. A2 will be assigned to the base of the triangles; B2 for the right angle side and C2 for the hypotenuses. First look for the size of the hypotenuses. The formula is as follows:

  For the bigger triangle:

        C2 = A2 + B2 which is equivalent to Hypotenuse = square root of A2 + B2
        C2 = 12’ x 12’ + 14’ x 14’
        C2 = 144 sq. ft + 198 sq. ft
        C2 = 342 sq. ft.

  • Using your calculator, enter 342 and press the square root sign, giving you 18.49 feet that will be the size of the hypotenuse for the larger triangle. Do the same for the smaller triangle. The resulting size of the hypotenuse will be 16.12 feet.
  • When you combine all the numbers that are now revealed for the perimeter of the triangle, the sum of all the numbers will be 54.61 feet. The height of the wall is 10 feet. Multiplying the perimeter of the triangle with the height of the wall which is 54.61’ x 10’ will give you an area of 546.10 square feet.

Finding the cubic feet of an area can be easy and fascinating as long as you understand how the mathematical formula works. Otherwise it will just be a jumble of numbers. Look up different mathematical formulas to find the total area in cubic meters of different shapes. The web has plenty of sites to visit where easy-to-follow tutorials are available.


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