Circles: Circumference, Area, Arcs, Chords, Secants, Tangents, Power of the Point. Theorems. All the links are here

Circles, arcs, chords, tangents ...

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Power Of the Point

Circumference of Circle

$$2\pi \cdot r \\ \pi \cdot diameter$$

Area of Circle

$$\pi \cdot r ^{2}$$

Theorems, Formula Circles Quiz

To solve this probelm, you must remember how to find the meaure of the interior angles of a regular polygon. In the case of a pentagon, the interior angles have a measure of (5-2) •180/5 = 108 °. Therefore, each inscribed angle creates an arc of 216°

Use the inscribed angle formula and the formula for the angle of a tangent and a secant to arrive at the angles

• mBDE = 72 °
• mBFC = 72 °
• mAGD = ½(144 −72) = 36 °

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