Urgent math problem Find the area of a small semicircle

The diameter of the pot surface is equivalent to the bottom of the bow, so r2=(20)2+(r-9)2 is solved to obtain r=481 18

Area s = s fan - s three =

The method is like this, and the result is calculated for yourself)

The ground floor is wrong. Let the radius r

r-9)^2+20^2=r^2

Solve the equation to get r = 481 18

The problem is.

What is the angle of the sector that is calculated first?

How to find its area.

This "pot" is a standard bow.

Bow area The area of the sector where the bow is located The area of the triangular part of the sector where the bow is located;

In this question: bowstring 40, arrow height 9

The bow contains radians a 2*=

The bow corresponds to the radius of the circle r [(20 2+9 2).

The bow corresponds to the sector area s1 r 2 a 2 =

The bow corresponds to the triangular area s2

Pot area s1-s2=

The approximate formula for the area of the bow is 2 3 l h, where l is the chord length and h is the sattal height.

The exact formula for calculating the area of the bow is attached.

s＝r2/2·(π/180-sinα)

r2arccos[(r-h)/r] -r-h)(2rh-h2)1/2παr2/360 - b/2·[r2-(b/2)2]1/2r(l-b)/2 + bh/2

Where: l arc length.

b Chord length. h Sagittal height.

r radius. The degree of the central angle.

Finally, the calculation formulas of the area and volume of various geometric figures are attached, which is completely refreshing:

The radius of this semicircle is 9 squared + 20 squared, that is, the side line when viewed from the side, and the area of the semicircle can be calculated.

The algorithm on the fifth floor is correct, and the answer is 125

Solution: The circumference of a half-lifted trapped circle = diameter Pi 2 + diameter = diameter (pi disturbance mode 2 + 1) = meters. So.

Radius of the semicircle =

50 2=25 25 25 sq.m.).

Is the diameter 6cm?

That's the radius of 3cm

The area of a circle with a radius of 3cm = 3 * 3 * = 9 Since it is a semicircle, it is a half circle = 9 2 = square centimeters.

The formula for the area of the circle is: s = r2 (you can take an approximate value here, or you can keep it without taking it, depending on the requirements of the question).

The diameter of this semicircle is 6cm

Then the radius is 3cm

Circle area = 3 * 3 * = 9

Because it is a semicircle, it = 9 2 = square centimeters.

Circle area = 3 * 3 * = 9

Since it is a semicircle, it is a semicircle = 9 2 = square centimeters.

This is not a semicircle. It should be called a bow.

Find the radius first:

80/2）²+r-15）²=r²

40²+r²-30r+225=r²

1600+225-30r=0

30r=1825

r=365/6

Find this fan angle again:

tgθ=（80/2）/（r-15）

arc tg 48/55=≈

Find the area of the sector minus the area of the triangle below.

I guess that's fine.

Bow area Sector area Area.

According to the Pythagorean theorem.

r²=a²+(r－h)²

It is known that a = 40 and h = 15

So r=(40 +15) 30=365 6 central angle = 2asina r=2asin40 (365 6) so sector area = r

Area=80*(r h)2=

So the arch area =

1. Find the central angle first.

2. Find the sector area (a 360 * circle area).

3. Use the sector area to subtract the triangle area (40*25) cm

Go and search for the sector area formula calculation.

The formula for calculating the area of a semicircle:

1. The area of the semicircle Pi and the square of the radius 2. Letter formula: s semicircle = r 2.

2. The circumference of the semicircle = pi radius + diameter. c semicircle = r + 2r.

Let the radius be r

r²=(2050÷2)²+r-410)²820r=1218725

r=centered=2xarcsin(2050 2

Area = Bring on your behalf.

Assuming that the base length of the bow is 2d and the height is h, then the radius r can be calculated as follows: h= , d=,

I don't know if Jun Suoyun has no ,,, map,,, no data,,, you are really funny.

The part of the semicircle The semicircle is a figure surrounded by curves and straight lines, it is half of the circle, and the position of the center of the semicircle is the position of the center of its concentric circles, and there is only one.

Half circle in diameter, but with an infinite number of radii, with an axis of symmetry.

The relevant formula for a half-circle.

The formula for the circumference of a semicircle = pi radius + diameter.

It is represented by a letter formula as:

c half = r + 2r

The area formula for a semicircle = pi radius radius 2

It is represented by a letter formula as:

S half = r2 2

The bow height is, then you make the perpendicular line of the string from the center of the circle and extend it to the arc, you can get that the length of the perpendicular segment from the center of the circle to the chord is the radius minus the bow height. The chord length is 30, so the triangle area is easy to find, the sector area, the radius is there, the main thing is the angle of the central angle, use the cosine theorem to calculate it.

Question 1:

The radius ratio is 1:2, the area ratio is 1:4, and because it is a semicircle, the final ratio is 1:2 The specific calculation method:

Let the radius of the minor circle be r, then the radius of the great circle is 2r

The area of the small circle is = r

The area of the semicircle is = (2r) 2=2 r

Small circle area: Half circle area = r:2 r = 1:2 Question 2:

What is formed is a ring.

Area s = (8 -6) = 28

Let the radius of the minor circle be x, then the radius of the major circle is 2x

Small circle area: Great circle area = x : 2x) half = 1:2

I didn't understand the 、、、 in the second question

1 Suppose the radius of the semicircle is 2a

The area of the semicircle is 2a 2 2a

The area of the small circle is a a

So the area of the small circle is one-half of the area of the semicircle.

2 (After rotation, the figure is a concentric circle, the minor circle is the radius of BC, and the large circle is the radius of AC).

The area of the great circle is 64

The area of the small circle is 36

The area of the gap between the minor circle and the large circle is 28

Let the radius of the small circle be x, and the diameter of the small circle is 2x, then the radius of the semicircle is 2x, the area of the semicircle is 2x, and the area of the small circle is x, so it accounts for 1/2