A lunette is a semicircular window that is sometimes placed above a doorway or above a rectangular window. A certain lunette has
a diameter of 40 in. To the nearest square inch, what is the area of the lunette?
The area of the lunette is ≈ ____ in2.
The area of the lunette is ≈ ____ in2.
1 answer:
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A (4,8) and b (7,2) and let c (x,y)
A , B and C are col-linear ⇒⇒⇒ ∴ slope of AB = slope of BC
slope of AB = (2-8)/(7-4) = -2
slope of BC = (y-2)/(x-7)
∴ (y-2)/(x-7) = -2
∴ (y-2) = -2 (x-7) ⇒⇒⇒ equation (1)
The ratio of AB : BC = 3:2
AB/BC = 3/2
∴ 2 AB = 3 BC
= <span>
eliminating the roots by squaring the two side and simplifying the equation
∴ 4 * 45 = (x-7)² + (y-2)² ⇒⇒⇒ equation (2)
substitute by (y-2) from equation (1) at </span><span>equation (2)
4 * 45 = 5 (x-7)²
solve for x
∴ x = 9 or x = 5
∴ y = -2 or y = 6
The point will be (9,-2) or (5,6)
the point (5,6) will be rejected because it is between A and B
So, the point C = (9,-2)
See the attached figure for more explanations
</span>
A , B and C are col-linear ⇒⇒⇒ ∴ slope of AB = slope of BC
slope of AB = (2-8)/(7-4) = -2
slope of BC = (y-2)/(x-7)
∴ (y-2)/(x-7) = -2
∴ (y-2) = -2 (x-7) ⇒⇒⇒ equation (1)
<span>The distance
between two points (x₁,y₁),(x₂,y₂) = d
</span>
The ratio of AB : BC = 3:2
AB/BC = 3/2
∴ 2 AB = 3 BC
eliminating the roots by squaring the two side and simplifying the equation
∴ 4 * 45 = (x-7)² + (y-2)² ⇒⇒⇒ equation (2)
substitute by (y-2) from equation (1) at </span><span>equation (2)
4 * 45 = 5 (x-7)²
solve for x
∴ x = 9 or x = 5
∴ y = -2 or y = 6
The point will be (9,-2) or (5,6)
the point (5,6) will be rejected because it is between A and B
So, the point C = (9,-2)
See the attached figure for more explanations
</span>