What is the radius of 3.5 cm?

The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumference of two circles.

Let the radius of the bigger circle be R cm. and radii of two smaller circles are r1and r2, then according to question.

2πR = 2πr1 + 2πr2
⇒    2πR = 2π (19) + 2π (9)

Hence, radius of the circle be 28 cm.

Draw a circle with a radius of 3.5 cm. Take the point K anywhere on the circle. Draw a tangent to the circle from K (without using the center of the circle)

1. Draw a circle of radius 3.5 cm and take any point K on it.
2. Draw chord BK of any length and an inscribed ∠BAK of any measure.
3. By taking A as centre and any convenient distance on compass draw an arc intersecting the arms of ∠BAK in points Q and R.
4. With K as centre and the same distance in the compass, draw an arc intersecting the chord BK at point S.
5. Taking radius equal to QR and S as centre, draw an arc intersecting the previously drawn arc. Name the point of intersection as P.
6. Draw line KP.
   Line KP is the required tangent to the circle.

Concept: Construction of a Tangent to the Circle at a Point on the Circle

  Is there an error in this question or solution?

A circle is the path covered by a point which moves in such a way that its distance from a fixed point always remains constant. The fixed point is called the centre and the constant distance is called the radius of the circle. Hence, a circle can be drawn if its centre and radius are known.

Construction: Draw a circle of radius 3.5 cm.

• Step 1: Mark a point O on a sheet of paper, where a circle is to be drawn.
• Step 2: Take a pair of compasses and measure 3.5 cm using a scale.
  
  
• Step 3: Without disturbing the opening of the compasses, keep the needle at mark O and draw a complete arc holding the compasses from its knob. After completing one complete round, we get the desired circle.
  

Read More:

Here is the answer to questions like: how to find the area of a circle with radius 3.5 cm?

Circle Calculator

Use the this circle area calculator below to find the area of a circle given its radius, or other parameters. To calculate the area, you just need to enter a positive numeric value in one of the 3 fields of the calculator. You can also see at the bottom of the calculator, the step-by-step solution.

Here a three ways to find the area of a circle (formulas):

See below some definitions related to the formulas:

Circumference

Circumference is the linear distance around the circle edge.

Radius

The radius of a circle is any of the line segments from its center to its perimeter. The radius is half the diameter or r = d2.

Diameter

The diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. The diameter is twice the radius or d = 2·r.

The Greek letter π

π represents the number Pi which is defined as the ratio of the circumference of a circle to its diameter or π = Cd . For simplicity, you can use Pi = 3.14 or Pi = 3.1415. Pi is an irrational number. The first 100 digits of Pi are: 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 ...

Note:

If you input the radius in centimeters, you will get the answer in square centimeters (cm²), if in inches, will get the answer in square inches (in²) and so on ...

Circumference is often misspelled as circunference.

While every effort is made to ensure the accuracy of the information provided on this website, neither this website nor its authors are responsible for any errors or omissions. Therefore, the contents of this site are not suitable for any use involving risk to health, finances or property.