geometry question?

Question

how do you construct the tangenat to a circle from a point on the cirlcle.

Answer 1

I can probably show you on Y! Messenger, but here's how you can do it...

Draw a line from the center of the circle, passing through the point you want, and PAST the outside of the circle extending a distance farther than the radius of your circle.

Using your compass, measure your radius, and mark (call it point B) that same distance from the POINT to the extended line you drew past the circle. (Now your point is the midpoint between the center and point B you made, also the radius and the distance between your point and the mark, are the same measurement)

Again using your compass, make a mark from BOTH your center and point B so that they intersect somwhere above or below your point.

The line passing through that intersection and your point is the tangent line you are looking for.

All this is much easier if I show you instead of trying to explain it to you, but I hope it works. Otherwise I think you can message me on Y! Messenger and I might be able to help you.

Good luck!

Answer 2

first find the slope of the line from the center of the circle to the point using the equation

m[1] = ( y[2] - y[1] ) / ( x[2] - x[1] )
where
x[1] & y[1] is the center of the circle
x[2] & y[2] is the point on the circle

next find the perpendicular of this slope using the equation
m[2] = - ( 1 / m[1] )

finally using the line equation sub in y[2], m[2] & x[2]
y - y[2] = m[2] ( x - x[2] )

this line will be the tangent to a circle from a point on the circle

Answer 3

The key to constructing (and understanding) a tangent line to a circle is that it is perpendicular to a radius of a circle.

In other words to construct a tangent line to a circle:
1. Pick the point on the circle you want to be tangential
2. Draw the radius of the circle that connects that point to the center of the circle
3. Draw a line through the tangential point that is perpendicular to the radius you just drew

And you've got a tangent to a circle.

Answer 4

You should know that the tangent to a circle at a point on it is perpendicular to the radio passing through that point.
So If O is the center and P the point draw OP and the perpendicular to it at P which is the tangent