[color=#0000ff]In the next applet you have to drag the points A,B,C and D and make the green and red lines parallel and perpendicular to each other. Slope of line joining A and B is [/color][math]m_1[/math][color=#0000ff] and slope of line joining C and D is [/color][math]m_2[/math][color=#0000ff].[br]Observe the values of these slopes when you drag.[/color]

In the following exercise you will be shown equations of two lines in slope intercept forms. Identify which pair is parallel and which are perpendicular. Click the "Try another question like this one " as many times as you like. After a few trials you should be sure of the answer.