Math Problem Statement

Find the area of the blue shaded region in a circle where a sector with a central angle of 150° is shaded, and the radius of the circle is 7 cm.

Solution

The problem asks to find the area of the blue shaded region in a circle, where a sector with a central angle of 150150^\circ is shaded, and the radius of the circle is 7 cm.

Step-by-Step Solution:

  1. Area of the full circle: The formula for the area of a circle is:

    Acircle=πr2A_{\text{circle}} = \pi r^2

    Where r=7r = 7 cm, so:

    Acircle=π×72=π×49153.94cm2A_{\text{circle}} = \pi \times 7^2 = \pi \times 49 \approx 153.94 \, \text{cm}^2

  2. Area of the sector: The area of a sector is given by the formula:

    Asector=θ360×AcircleA_{\text{sector}} = \frac{\theta}{360^\circ} \times A_{\text{circle}}

    Where θ=150\theta = 150^\circ. So:

    Asector=150360×153.9464.14cm2A_{\text{sector}} = \frac{150}{360} \times 153.94 \approx 64.14 \, \text{cm}^2

  3. Subtract the white region (sector) from the total circle area: The white region (which is a sector) has already been calculated. Since the blue region consists of the remainder of the circle:

    Ablue shaded region=AcircleAsector=153.9464.1489.8cm2A_{\text{blue shaded region}} = A_{\text{circle}} - A_{\text{sector}} = 153.94 - 64.14 \approx 89.8 \, \text{cm}^2

Final Answer:

The area of the blue shaded region is approximately 89.8 cm².

Would you like more details or have any questions?

Here are some related questions for further practice:

  1. How do you find the area of a sector with a different angle?
  2. How would you calculate the area of a circle if the radius was doubled?
  3. What is the formula for finding the circumference of a circle?
  4. How would you find the perimeter of the shaded region?
  5. What if the angle was given in radians instead of degrees?

Tip: Always ensure your angle is in the correct units (degrees or radians) before applying it to sector area formulas.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Area
Sector Area
Angle Measurement

Formulas

Area of a Circle = πr²
Area of a Sector = (θ/360) * πr²

Theorems

Sector Area Formula

Suitable Grade Level

Grades 7-9