Circle Theorem - Inscribed Angle in a Semi-Circle is 90°

Circle Theorem - Inscribed Angles is 90° - How it Works - Video

Example 1

Example 1:

Example 2

Example 2:

Example 3

Example 3a:

To find the arc length of a circle we need the radius and the central angle. Then we can use the formula, Arc Length = 2πr * θ/360°. Now our first step is substitute the radius and the central into the formula.

So we have arc MNO = 2π(10) * (225°)/360°.

Next multiply the numbers next to pi ==> 20π * (225°)/360°.

Now we simplify the 225 and the 360 by dividing each number by 45° ==> 20π * 5/8.

Next we multiply the two numbers 20 and 5/8 ==> 100/8*π.

Now we simplify the 100 and 8 by dividing each number by 4 ==> 25/2*π cm. And that is the final simplified version. Sometimes the answer needs to be in decimal so we multiple 25/2 and π ==> 39.27 cm is another possible result.

Live Worksheet

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