Thursday

October 2, 2014

October 2, 2014

Posted by **jigna** on Sunday, February 25, 2007 at 6:45am.

Use trigonometry.

Let the slope of a line from A to B be m1. Let the slope of a perpendicular line from A to C be m2. The tangent (or slope) of the line between these two lines is:

tan (a - b) = (m1 + m2)/(1 - m1 m2)

a and b are the ANGLES of the two lines, measured from the x axis.

(This is a trigonometric identity)

Now IF m1 m2 = -1, then

tan (a-b) = (m1 - 1/m1)/0 = infinity

therefore the angle between the two lines is 90 degrees.

**Answer this Question**

**Related Questions**

Geometry - Prove that the tangents to a circle at the endpoints of a diameter ...

Geometry HELP - Using coordinate geometry to prove that the diagonals of a ...

algebra 1 - he slope of a line is negative two-thirds. What is the slope of a ...

Writing this equation - how do I write the equation of a line perpendicular to ...

Geometry - How do I write an equation of a line perpendicular to the graph of -...

MATH - For the floor plans given in exercise27, determine whether the side ...

algebra - Find the slope of any line perpendicular to the line through points (0...

Algebra - Can someone check my answers? 1. Write the equation of the line that ...

Algebra 1 - 1.To solve the linear system below, which substitution of unkowns is...

MATH! - What type of lines have a slope of zero? Write the equation of a line ...