The area of a circle π R ^ 2 what are 2 π R and π D

The area of a circle π R ^ 2 what are 2 π R and π D

2 π R and π D are the circumference of a circle
Where D is the diameter of the circle

Find the area of the circle d = 6 decimeters

Diameter 6
The radius is 3
So the area of the circle = 3.14 × three × 3 = 28.26 square decimeters
If it helps you, please remember to adopt it, O (∩ ∩) O thank you

Let f (x) = ex + SiNx, G (x) = ax, f (x) = f (x) - G (x) (1) If x = 0 is the extreme point of F (x), find the value of real number a; (2) If x > 0, the image of function y = f (x) is always above the image of y = f (- x). Find the value range of real number a

(1) F (x) = ex + SiNx ax, the derivative function can be obtained as f ′ (x) = ex + cosx-a. because x = 0 is the extreme point of F (x), f ′ (0) = 1 + 1-A = 0, a = 2. When a = 2, if x < 0, f ′ (x) = ex + cosx-a < 0; If x > 0, f '(x) = ex + cosx-a > 0; ‡ x = 0 is the minimum of F (x)

A problem about one step of derivative in mathematics of college entrance examination Given the parabola C1: y = x2 + 2x, and C2: y = - x2 + A, if the straight line L is the tangent of C1 and C2 at the same time, l is the common tangent of C1 and C2, and the line segment between two tangent points on the common tangent is called the common tangent line segment (1) A what value does C1 and C2 have and only have one common tangent? Write the equation of this common tangent (2) If C1 and C2 have two common tangents, it is proved that the corresponding two common tangents are bisected by each other (2) It is proved that when (1) is known, C1 and C2 have two common tangents Let the tangent point of a common tangent line be p (x1, Y1) and Q (X2, Y2), where p is on C1 and Q is on C2, then X1 + x2 = - 1, Why X1 + x2 = - 1! Very anxious, thank you!

For C1, the tangent slope of Y '= 2x + 2 at point X1 is 2x1 + 2
For C2, y '= - 2x, the tangent slope at X2 is - 2x2
Because it is a common tangent, the slopes are equal, i.e
2x1+2=-2x2
The shift is the result you see: X1 + x2 = - 1

Let f (x) = e ^ x-ax-2 (1) Find the monotone interval of F (x); (2) If a = 1, K is an integer, and when x > 0, (x-k) f '(x) + X + 1 > 0, find the maximum value of K Children's shoes who have done the number of papers in the national volume of this year's new curriculum standard must be very familiar with it! Is there a good way?

【1】 The solution of the monotone interval f '(x) = e ^ x-a needs to be discussed according to the range of A. [2] a = 1, then: F' (x) = e ^ X-1, then this inequality is: (x-k) (e ^ x-1) + X + 1 > 0. Let g (x) = (x-k) (e ^ x-1) + X + 1, then: G '(x) = (x-k + 1) e ^ x, then: G (x) increases at xk-1, so

Who can tell me about the relationship between derivative and differential of univariate function Is differentiable?

Landlord friends, the commonly said derivative is actually the abbreviation of "derivative function". People have evolved slowly during scientific research and research. It is not like the derivative said by friends on the third floor that the derivative is a number. To be exact, the derivative value is a number. In addition, in another function, derivative and differential are a pair of inverse operations. If a function has derivative