The side area of a cone is 8 π CM & # 178;, and its axial section is an equilateral triangle

The side area of a cone is 8 π CM & # 178;, and its axial section is an equilateral triangle

πrl=8π
∴rl=8
The axis section is an equilateral triangle
∴l=2r
∴2r²=8
∴r=2
The area of axial section is √ 3 · (2 × 2) & # 178; / 4 = 4 √ 3cm & # 178;

The bottom radius of the cone is r, the cross section of the axis is a right triangle, and the surface area of the cone is calculated

Let the bottom radius of the cone be r, the height be h, and the generatrix length be l (L ^ = R ^ + H ^)
∵ the expanded side view of a cone is a sector with a radius of L and an arc length of 2 π R
The cone side area = (1 / 2) (2 π R) l = π RL

If the radius of the bottom of a cone is known to be 1 and the section of its axis is an isosceles right triangle, then the surface area of the cone is

The area of the bottom circle = π X1 ^ 2 = π the perimeter of the bottom circle = 2 π the section of the axis is an isosceles right triangle, so the cone generatrix = √ 2 / 2 because the side expansion of the cone is a sector, so the area of the side expansion of the cone = (1 / 2) × the perimeter of the bottom circle × the cone generatrix = (1 / 2) × 2 π× (√ 2 / 2) = (√ 2 / 2)

Is the orthographic projection of the apex of a cone on the bottom necessarily the center of the circle on the bottom

Cone is divided into straight cone and oblique cone. The normal projection of the vertex of straight cone on the bottom surface must be the center of the circle on the bottom surface, but oblique cone is not. Generally, we only discuss straight cone, because oblique cone does not satisfy the definition of body of revolution

The symmetry axis of the image of quadratic function y = (x-1) 2-2 is a straight line______ ．

∵ y = (x-1) 2-2 is the vertex form of parabola. According to the coordinate characteristics of vertex form, the axis of symmetry is a straight line x = 1

Quadratic function y = (x-2009) ^ 2 the symmetry axis of image is x =?
The "^ 2" after brackets refers to the second power

X=2009
Y = (x-a) ^ 2 + B in this form, the axis of symmetry is x = a

The symmetry axis of image of quadratic function y = - (x + 3) (X-2) is

x=-1/2

The symmetry axis of the image of quadratic function y = 2 (x-3) (x + 1) is_

Y = a (x + Q) (x + W) axis of symmetry x = - (W + Q) / 2
x=-(-3+1)/2=+1

How to translate the image of function y = - x2 in quadratic function exercises can get the image of function y = - x2-8x-7

y=-x^2-8x-7=-(x^2+8x+7)=-(x+4)^2+9
So move 4 units to the left and 9 units up

On the translation of inverse scale function?
How to translate? For example, y = 2 / x, 2 units up, and 3 units up. What's the result

Top plus bottom minus, left plus right minus
Translate 2 upward, add 2 after the whole analytical expression, and decrease downward;
Shift 3 to the left to replace x with x + 3 and x-3 to the right
So the result of y = 2 / x, 2 units up and 3 units up is y = (2 / x-3) + 2