Home Graphs Geometry Help Frac & Dec Percentages Math Tools Math Tables Glossary Authors Page Geometry Perpendicular and Parallel Lines Parallel Lines Parallel lines are two lines that are across from each other. The parallel lines never meet each other. Perpendicular lines Perpendicular lines are lines that meet each other. The perpendicular lines make right angles. Perimeters, Area, and Volume How to find the perimeter of a polygon 1. Measure all of the sides on the polygon in either centimeters or inches on a ruler. 2. Add all of the inches or centimeters together and you get the perimeter. How to find out an area of a circle 1. Measure the radius with a ruler. 2. Multiply the radius by itself. Multiply the number you got in step 2 by pi (3.14). How to find an area of a polygon 1. Measure one side vertically and one side horizontally in centimeters or inches with a ruler. Multiply the measurements together and you have your answer How to find the volume of a 3 dimensional objects 1. Measure the length, the width, and the height with a ruler. 2. Multiply the length times the width times the height and you have your answer