Circles Review

Circles Review

Circle Segments, Circle Angles, Sector Area, Circle Equations

Circle Segments

• part(part)=part(part)

• outside(whole)=outside(whole)

• tangent²=outside(whole)

• tangent=tangent

Multiple Choice

What is the value of x?

• 10
• 4
• 5
• 8

Circle Angles

• Central Angles: angle = arc

• Inscribed Angles: angle = 1/2arc

• Interior Angles: angle = 1/2(arc + arc)

• Exterior Angles: angle=1/2(big arc - little arc)

Multiple Choice

Find the measure of arc AB.

• 17
• 34
• 68
• 146

Sector Area

•  $\theta$  is the central angle

• r is the radius

• Remember if they gave you the diameter, divide by 2 to get the radius

Multiple Choice

Find the area of the shaded sector of circle O. The radius is 6 inches and the central angle is 100°. Express answer to the nearest tenth of a square inch.

• 25.2 in²

• 28.5 in²

• 31.4 in²

• 38.2 in²

Circle Equations

• (h,k) is the center, but remember to make the signs OPPOSITE.

• r is the radius

• To WRITE the equation: square the radius

• FROM the equation: take the square root of r²

Multiple Choice

Write the equation of a circle with center (7, 0) with radius 3.

• (x - 7)² + y² = 9
• x² + (y -7)² = 9
• (x - 7)² + y² = 3
• x² + (y -7)² = 3