How To Solve Geometry Calculations

Geometry calculations often involve determining the perimeter and area of polygons and the volume of solid figures. Perimeter measures the length around a flat shape while area measures the surface of the shape. Volume measures the capacity of a solid figure. To solve geometry calculations, use formulas when measuring perimeter, area and volume.

Step 1

Determine the formula or method needed to find the perimeter of the polygon you are measuring. Use the formula P = 4_s (perimeter = four times the length of one side) to find the perimeter of a square. To find the perimeter of a rectangle use the formula P = 2_l + 2*w (perimeter = two times the length plus two times the width). To find the perimeter of other polygons, simply add up the sides.

Step 2

Replace the variables with numbers. Use a ruler to determine the value of each side of the polygon. If the measurements are provided for you, simply insert the correct numbers into the formula.

Step 3

Solve the formula to determine perimeter. When using the formula for a rectangle, remember to multiply the length times two and the width times two and then add the two products together.

Step 1

Determine if the figure is a triangle, square, rectangle or parallelogram. A triangle has three sides, and polygons have four sides. Both squares and rectangles have four right angles. However, a square has four equal sides while a rectangle has only two equal sides. A parallelogram has two sets of parallel sides, but the angles do not measure 90 degrees.

Step 2

Select the correct area formula for the polygon you are measuring. Use A = ½(b)h/2 (area = one half base times height or base times height divided by two) to determine the area of a triangle. To find the area of a square, use A = ss (area = side times side). Find the area of a rectangle using the formula A = lw (area = length times width). The area of a parallelogram can be found using the formula A = bh (area = base times height).

Step 3

Solve the formula to determine the area. Replace the variables with values for the base, height, length and width, and complete the equation.

Step 1

Determine the length, width and height of the solid figure. Use a ruler to measure each, and determine the value.

Step 2

Enter the values for each into the formula V = lwh (volume = length times width times height). First enter the value for length, then the value for width and then the value for height.

Step 3

Solve the equation to determine volume. First multiply the length by the width. Then multiply the product of those two by the height.