How to find the radius of a circle? We need a formula

It depends on the conditions given
If the diameter is given, then: r = D △ 2
If the circumference is given, then: r = C △ π △ 2
If we give the area, then: r = s △ π and then square it

A formula for finding the radius of a circle
Let's draw an arc from point a to point B. We know that the distance between a and B is 113. The arc height is 20. What's the radius

The formula you need to know is called the residual circle formula. Let the diameter of the circle be D, the chord length be l, and the chord height (also known as the vector height) be h. The formula is d = L / 2 × L / 2 △ H + H, which means that the diameter is equal to half of the chord, and the chord height plus one chord height. If the diameter is found, the radius will be found
That is: diameter d = (113 / 2) * (113 / 2) / 20 + 20 = 179.6125
Radius r = 179.6125/2 = 89.80625

A formula for finding the radius of a circle
You just tell me r = That's it!

r=(d/2)

What are the parallel line theorems

Definition of parallel line: in the plane, two lines that never intersect are called parallel lines
Properties of parallel lines: if two lines are parallel and cut by three lines, then:
1. The same position angle is equal;
2. The internal stagger angles are equal;
3. The ipsilateral internal angle complements each other;
4. The outer corner of the same side complements each other
The judgment theorem of parallel line: two straight lines are cut by the third straight line, if:
1. If the same angle is equal, the two lines are parallel;
2. If the internal stagger angles are equal, the two lines are parallel;
3. The two lines are parallel;
4. If the external angle of the same side complements each other, the two lines will be parallel!

Students have to wear sports shoes in the P.E.class

What do students have to wear in the P.E.class?

When the distance between the center of gravity g of triangle ABC and the side of BC is 5 / 3, BC = 6, then the area of triangle ABC is
Please come in two hours

S ⊿ ABC = (1 / 2) × BD × H = (1 / 2) × 6 × [3 × (5 / 3)] = 15 (area unit)

The greatest common factor of the two numbers is 14, and the least common multiple is 84. What are the two numbers?

These two numbers are 28 and 42 respectively, ∵ if the greatest common factor is 14, then these two numbers must be multiples of 14; if the least common multiple is 84, then these two numbers must be factors of 84, ∵ 84 decomposes 2 * 2 * 3 * 7, if the greatest common factor is 14, then these two numbers are 2 * 7 * 2 = 28 and 2 * 7 * 3 = 42 respectively

Proof: the ratio of the corresponding center line of similar triangle is equal to the similar ratio. Complete answer! Need graph

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The greatest common divisor of two positive integers is 6, and the least common multiple is 90. There are () pairs in the first pair of large numbers composed of two positive integers satisfying the condition

Decomposition quality factor
90=2*3*3*5
6=2*3
The numbers a and B must contain 2 * 3, and the other two factors 3 and 5 in 90 can belong to two different numbers or the same number
But it can't belong to two numbers at the same time
So the answer is 2 * 3 * 5 and 2 * 3 * 3 or 2 * 3 * 3 * 5 and 2 * 3
So the answer is 30, 18 or 90, 6

Let a (- 1,0) and B (1,0) pass through two points a and B respectively, and the product of the slopes of L1 and L2 is - 4?

Let the intersection be (x, y)
The product of the slopes of lines L1 and L2 is
[y/(x+1)]*[y/(x-1)]=-4
Simplify to y ^ 2 = - 4 (x ^ 2-1)
That is 4x ^ 2 + y ^ 2 = 4 (x is not equal to 1 and X is not equal to - 1)
Two lines can't intersect on the X axis. They will coincide

How to find the radius of a circle? We need a formula