Ratio of sides

Calculate the area of a circle that has the same circumference as the circumference of the rectangle inscribed with a circle with a radius of r 9 cm so that its sides are in ratio 2 to 7.

Correct result:

S =  157.617 cm2

Solution:

r=9 cm r2=(a/2)2+(b/2)2 a:b=2:7  r2=(a/2)2+((7/2 a)/2)2 r2=a2/4+a2 (7/4)2  a=r/(1/4+(7/4)2)=9/(1/4+(7/4)2)4.945 cm  b=7/2 a=7/2 4.94517.3074 cm  o=2 (a+b)=2 (4.945+17.3074)44.5048 cm  o=2π r1  r1=o/(2π)=44.5048/(2 3.1416)7.0832 cm   S=π r12=3.1416 7.08322=157.617 cm2r=9 \ \text{cm} \ \\ r^2=(a/2)^2 + (b/2)^2 \ \\ a:b=2:7 \ \\ \ \\ r^2=(a/2)^2 + ((7/2 \cdot \ a)/2)^2 \ \\ r^2=a^2/4 + a^2 \cdot \ (7/4)^2 \ \\ \ \\ a=r / (\sqrt{ 1/4+(7/4)^2 })=9 / (\sqrt{ 1/4+(7/4)^2 }) \doteq 4.945 \ \text{cm} \ \\ \ \\ b=7/2 \cdot \ a=7/2 \cdot \ 4.945 \doteq 17.3074 \ \text{cm} \ \\ \ \\ o=2 \cdot \ (a+b)=2 \cdot \ (4.945+17.3074) \doteq 44.5048 \ \text{cm} \ \\ \ \\ o=2 \pi \cdot \ r_{1} \ \\ \ \\ r_{1}=o / (2 \pi)=44.5048 / (2 \cdot \ 3.1416) \doteq 7.0832 \ \text{cm} \ \\ \ \\ \ \\ S=\pi \cdot \ r_{1}^2=3.1416 \cdot \ 7.0832^2=157.617 \ \text{cm}^2



Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!


Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




Tips to related online calculators
Looking for help with calculating roots of a quadratic equation?
Check out our ratio calculator.
Pythagorean theorem is the base for the right triangle calculator.
See also our trigonometric triangle calculator.

 
We encourage you to watch this tutorial video on this math problem: video1   video2

Next similar math problems:

  • Rectangular garden
    garden_21 The sides of the rectangular garden are in ratio 1: 2. The diagonal has a length of 20 meters. Calculate the area and perimeter of the garden.
  • Circumference - a simple
    circle_radius What is the ratio of the circumference of any circle and its diameter? Write the result as a real number rounded to 2 decimal places.
  • Cathethus and the inscribed circle
    RightTriangleInradius In a right triangle is given one cathethus long 14 cm and the radius of the inscribed circle of 5 cm. Calculate the area of this right triangle.
  • RT 11
    right_triangle Calculate the area of right tirangle if its perimeter is p = 45 m and one cathethus is 20 m long.
  • The right triangle
    rt_tr540 The right triangle ABC has a leg a = 36 cm and an area S = 540 cm2. Calculate the length of the leg b and the median t2 to side b.
  • Isosceles triangle
    triangles_8 Calculate area and perimeter of an isosceles triangle ABC with base AB if a = 6 cm, c = 7 cm.
  • Equilateral triangle
    rs_triangle_1 The equilateral triangle has a 23 cm long side. Calculate its content area.
  • ISO Triangle V2
    triangle_3 Perimeter of RR triangle (isosceles) is 474 m and the base is 48 m longer than the arms. Calculate the area of this triangle.
  • Median in right triangle
    rt_triangle In the rectangular triangle ABC has known the length of the legs a = 15cm and b = 36cm. Calculate the length of the median to side c (to hypotenuse).
  • Inscribed circle
    inscribed_circle XYZ is right triangle with right angle at the vertex X that has inscribed circle with a radius 5 cm. Determine area of the triangle XYZ if XZ = 14 cm.
  • Inscribed rectangle
    circle_desc_rectangular The circle area is 216. Determine the area of inscribed rectangle with one side 5 long.
  • Inscribed circle
    vpisana The circle inscribed in a triangle has a radius 3 cm. Express the area of the triangle using a, b, c.
  • Inscribed rectangle
    rectangle_inside_circle What is the perimeter of a rectangle that is inscribed in a circle whose diameter is 5 dm long? Answer: 14 dm
  • RT and circles
    r_triangle Solve right triangle if the radius of inscribed circle is r=9 and radius of circumscribed circle is R=23.
  • Center traverse
    trianles It is true that the middle traverse bisects the triangle?
  • Tv screen
    tv2 The size of a tv screen is given by the length of its diagonal. If the dimension of a tv screen is 16 inches by 14 inches, what is the size of the tv screen?
  • Equation
    calculator_2 Equation ? has one root x1 = 8. Determine the coefficient b and the second root x2.