100% students answered this correctly
Area and Perimeter
1. Area of a triangle =12×Base ×height
2. Area of a triangle
=ss-as-b(s-c), where
s=a+b+c2
3. Area of an equilateral triangle
=34×Side2
4. Area of a circle =πr2
5. Circumference of a circle =2πr
6. Area of a sector of a circle =360°×πr2
7. Area of a square =Side2
8. Perimeter of a square =4×Side
9. Perimeter of a Rectangle
=2(length+breadth)
Area of a Rectangle = (length+breadth)
10. A rhombus is a parallelogram that has all the sides equal. In a rhombus, diagonals always bisect each other.
Area =12×d1×d2
11. A quadrilateral whose opposite sides are parallel is called a parallelogram. Diagonals of a parallelogram bisect each other. Area =Base ×Height
12. A trapezium is a quadrilateral with only two sides parallel to each other. Area =12 Sum of parallel sides × Height
In geometry, the straight lines which do not meet are called parallel. A line that crosses a pair of parallel lines is known as transversal. Watch and learn...
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If the diameter of a circle increases by 50 percent, by what percent [#permalink]
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If the diameter of a circle increases by 50 percent, by what percent will the area of the circle increase?A. 25%B. 50%C. 100%D. 125%
E. 225%
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Re: If the diameter of a circle increases by 50 percent, by what percent [#permalink]
My answer DIf the diameter increases 50%, the radius also increases 50%.The area would remain Pi(r^2)Say for example Radius increases from 10 to 15the area would increase from 100pi to 225pi.
therefore 125% increase.
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Re: If the diameter of a circle increases by 50 percent, by what percent [#permalink]
Bunuel wrote:
If the diameter of a circle increases by 50 percent, by what percent will the area of the circle increase?A. 25%B. 50%C. 100%D. 125%
E. 225%
radius = 2 dia 4area = 4pi50% increase in dia = 4*1.5 = 6radius = 3area = 9pi% change in area = 9pi-4Pi/ 4 pi = 125 % IMO D
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If the diameter of a circle increases by 50 percent, by what percent [#permalink]
Solution
Given:
- • The diameter of a circle increases by 50%
To find:
- • The percentage increase in area of the circle
Approach and Working: Let ‘d‘ be the initial diameter
- • Area = \(ᴨ\frac{d^2}{4}\) = A
- • Area = \(ᴨ(\frac{3d}{2})^2/4 = 9ᴨ\frac{d^2}{16} = \frac{9A}{4}\)
Answer: D
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Re: If the diameter of a circle increases by 50 percent, by what percent [#permalink]
Bunuel wrote:
If the diameter of a circle increases by 50 percent, by what percent will the area of the circle increase?A. 25%B. 50%C. 100%D. 125%
E. 225%
Solution:
If the diameter of a circle increases by 50 percent, the radius also increases by 50 percent. If we let the original radius = 10, the new radius = 15. Thus, we have:Area of the original circle = 10^2 x π = 100π Area of the new circle = 15^2 x π = 225π We use the percent change formula: (New - Old) / Old x 100. Therefore, the area of the circle increases by(225π - 100π)/(100π) x 100 = 125π/π = 125 percentAnswer: D
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Re: If the diameter of a circle increases by 50 percent, by what percent [#permalink]
20 Jun 2020, 14:30