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21 votes
Find the area of the circle x2 + y2 + 4x – 8y – 29 = 0. in sq.units

User Arcath
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1 Answer

30 votes
30 votes

Answer:

A ≈ 154 units²

Explanation:

the area (A) of a circle is calculated as

A = πr² ( r is the radius)

to calculate the area we require to know r

the equation of a circle in standard form is

(x - h)² + (y - k)² = r²

given

x² + y² + 4x - 8y - 29 = 0

collect x and y terms together and add 29 to both sides )

x² + 4x + y² - 8y = 29

obtain standard form for circle using the method of completing the square

add ( half the coefficient of the x/ y terms)² to both sides

x² + 2(2)x + 4 + y² + 2(- 4)y + 16 = 29 + 4 + 16

(x + 2)² + (y - 4)² = 49 = r² ← in standard form

Then

A = πr² = π × 49 ≈ 154 units² ( to the nearest whole unit )

User Olayinka
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3.1k points