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a. Area. = π (2.5) 2. r = 2.5 cm. ANSWER. The area of A is about 19.63 square centimeters. Use the formula for area of a circle. EXAMPLE 1. Find the indicated measure. SOLUTION. A = π r 2. Write formula for the area of a circle. Substitute 2.5 for r. = 6.25π.
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a. Area = π (2.5)2 r= 2.5 cm ANSWER The area of A is about 19.63 square centimeters. Use the formula for area of a circle EXAMPLE 1 Find the indicated measure. SOLUTION A = πr2 Write formula for the area of a circle. Substitute 2.5 for r. = 6.25π Simplify. ≈ 19.63 Use a calculator.
b. Diameter 113.1 = r2 π A = 113.1 cm2 ANSWER The radius is about 6 cm, so the diameter is about 12 centimeters. Use the formula for area of a circle EXAMPLE 1 Find the indicated measure. SOLUTION A = πr2 Write formula for the area of a circle. 113.1 = πr2 Substitute 113.1 for A. Divide each side by π. 6 ≈ r Find the positive square root of each side.
Find the areas of the sectors formed by UTV. Because m UTV = 70°, mUV = 70° and mUSV = 360° – 70° = 290°. Find areas of sectors EXAMPLE 2 SOLUTION STEP 1 Find the measures of the minor and major arcs.
mUV Area of small sector = πr2 360° 70° = π 82 360° Find areas of sectors EXAMPLE 2 STEP 2 Find the areas of the small and large sectors. Write formula for area of a sector. Substitute. ≈ 39.10 Use a calculator.
290° = π 82 360° ANSWER The areas of the small and large sectors are about 39.10 square units and 161.97 square units, respectively. mUSV Area of large sector = πr2 360° Find areas of sectors EXAMPLE 2 Write formula for area of a sector. Substitute. ≈ 161.97 Use a calculator.
1. Area of D ANSWER about 615.75 ft2 for Examples 1 and 2 GUIDED PRACTICE Use the diagram to find the indicated measure.
ANSWER about 205.25 ft2 for Examples 1 and 2 GUIDED PRACTICE Use the diagram to find the indicated measure. 2. Area of red sector
ANSWER about 410.50 ft2. for Examples 1 and 2 GUIDED PRACTICE Use the diagram to find the indicated measure. 3. Area of blue sector