# Two Tangents from One Point

Using Tangents to Circumscribe a Circle

Two tangents from a common point are congruent!

The interactive applet below will show you this rule. Just drag the points around the screen and you'll see that--no matter what--the lengths of the tangents, are always equal.

### Interactive Applet (html5)

Show Grid? Snap to Grid? Size Round to Update Speed (?)

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### Practice Problems

(Drawing not to scale)

Each side length that you know (5,3,4) is equal to the side lengths in red because they are tangent from a common point

Since two tangents from a common point (G and H) are congruent, $$GT = EG = 10$$, $$HT = HE = 10$$

Perimeter of quadrilateral = 10 + 10 + 10 + 10 = 40

What kind of quadrilateral is EGHT?

Since all four sides are congruent, it is a rhombus

• YC = ZC = 21
• BZ = XB = 19
• AX = AY = 20

Perimeter = AX + AY + BZ + XB + YC + ZC = 20 + 20 + 19 + 19 + 21 + 21 = 120

### Ultimate Math Solver (Free)

Free Algebra Solver ... type anything in there!