It is known that there are two points a and B in the two planes of dihedral angle α - L - β, and their projections in L are C, D, respectively It is known that there are two points a, B, a and B in the two planes of dihedral angle α - L - β. The projections of a, B, a and B in L are C, D, AC = 3, BD = 3, CD = 4 and ab = 5 respectively. The size of dihedral angle α - L - β can be obtained Why ∠ AEB = 90 °?

It is known that there are two points a and B in the two planes of dihedral angle α - L - β, and their projections in L are C, D, respectively It is known that there are two points a, B, a and B in the two planes of dihedral angle α - L - β. The projections of a, B, a and B in L are C, D, AC = 3, BD = 3, CD = 4 and ab = 5 respectively. The size of dihedral angle α - L - β can be obtained Why ∠ AEB = 90 °?

AD=√3^2+4^2=5
Make CE ‖ = BD through C on the plane where BD is located
AE=√AB^2-BE^2=√AB^2-CD^2=√5^2-4^2=3
CE=BD=3 AC=3
The ace is an equilateral triangle
∴∠ACE=60°
The dihedral angle α - L - β is 60 degrees

If the dihedral angle α - α β - β is 120 degrees, AC belongs to α, BD belongs to β, and AC ⊥ AB, BD ⊥ AB, ab = AC = BD = α, then the length of CD is
If you can tell me where the symbol "belongs" is by the way

Make AE ‖ and = BD.CE= (3) * A. de = a CD = 2A

In the plane rectangular coordinates, the coordinates of the center P of ⊙ P are (8,0), and the radius is 6, then the position relationship between the line y = x and ⊙ P is______ ．

As shown in the figure, make a vertical line of straight line y = x through point P, and the vertical foot is m. ∵ ∠ mop = 45 °, in RT △ mop, PM = op · sin 45 ° = 8 × 22 = 42 ＜ 6, so the straight line intersects the circle

In the plane rectangular coordinate system, the coordinate of the center P of the circle P is (8,0). If the circle P is tangent to the straight line y = x, then the radius r of the circle P is

Let the distance from point P to the straight line be l, then l and the straight line y = x and X axis form an isosceles right triangle. According to the bottom edge of 8, the value of l can be obtained. If the value of L is less than 6, it is intersection

In the plane rectangular coordinates, the coordinates of the center P of ⊙ P are (8,0), and the radius is 6, then the position relationship between the line y = x and ⊙ P is______ ．

As shown in the figure, make a vertical line of straight line y = x through point P, and the vertical foot is m. ∵ ∠ mop = 45 °, in RT △ mop, PM = op · sin 45 ° = 8 × 22 = 42 ＜ 6, so the straight line intersects the circle

If the radii of the two circles are 2 and 1 respectively, and the coordinates of the center of the circle are (1,0), (2,1), then the position relationship of the two circles is
A. Separation B. tangency C. intersection D. inclusion

To judge the position relationship between two circles, we only need to compare the sum or difference between the center distance and radius
Center distance d = √ [(2-1) &# 178; + (1-0) &# 178;] = √ 2
Sum of two radii R + r = 3
The difference between the two radii | R-R | = 1
Obviously 1

The center coordinates of the two circles are (root sign 3,0) and (0,1). If their radii are 3 and 5 respectively, the position relationship of the two circles is ()

Cut inside!
Draw the coordinate system, connect the two centers, through the Pythagorean theorem to calculate the distance of 2, and because 5-3 = 2, so the two circles inscribed! Not clear, please forgive me

If the center coordinates of the two circles are (root 3,0) (0,1) and the radii are 3 and 5 respectively, then the position relationship between the two circles
Such as the title

In Pythagorean theorem, the distance between the centers of a circle is found to be root (3 + 1) = 2
Because 5-3 = 2
So the two variables are inscribed

As shown in the figure, in the plane rectangular coordinate system, take point C (1,1) as the center and 2 as the radius to make a circle, intersect the x-axis at two points a and B, the parabola with the opening downward passes through points a and B, and its vertex P is on ⊙ C (1) (2) write out the coordinates of two points a and B; (3) try to determine the analytical formula of the parabola; (4) whether there is a point D on the parabola so that the line OP and CD are equally divided? If it exists, find out the coordinate of point D; if not, explain the reason

(1) Take ch ⊥ X axis, h as the perpendicular foot, ≁ ch = 1, radius CB = 2, ∵∠ BCH = 60 ° and ∵ ACB = 120 ° (2) ∵ ch = 1, radius CB = 2 ∵ HB = 3, so a (1-3, 0), B (1 + 3, 0); (3) from the symmetry of circle and parabola, we can know that the coordinates of the vertex P of parabola are (1, 3) let parabola be analytic

As shown in the figure, in the rectangular coordinate system, the line AB intersects the x-axis, and the y-axis is at points a (4,0) and B (0, - 3). The center of an existing moving circle with radius 1 is located at the origin, and it moves to the right at the speed of 1 unit per second, then it passes through the center______ Second, the moving circle is tangent to the line ab

Let ⊙ p be tangent to the line AB after x seconds, and make a vertical line of AB through P, and the perpendicular foot is Q, then PQ = 1; (1) when ⊙ P is tangent to the line AB on the left side of the line AB, AP = 4-x, obtained from △ Apq ∽ ABO, apab = pqbo, that is, 4 − X5 = 13, and the solution is x = 73; (2) when ⊙ P is tangent to the line AB on the left side of the line a, AP = 4-x