Tuesday
September 23, 2014

Homework Help: maths geometry

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

Find and write down a proof that the product of the gradients of two perpendicular lines is -1

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

First Name:
School Subject:
Answer:

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 ...

Search
Members