![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
The projection of a point on the coordinate axis of the space coordinate system How to find. Can give an example to illustrate, as long as I can understand. Success can be + points How to find it when drawing
(1.2.3)
Projection on X-axis (1.0.0)
It's equivalent to keeping the number of that axis
The rest is zero
In the space rectangular coordinate system, the distance from a certain point to the three coordinate axes is 1?
I made root 3, but the answer is root 6 / 2. Why?
√3
It's obvious that we use the Pythagorean theorem twice
Distance = √ {[√ (1 ^ 2 + 1 ^ 2)] ^ 2 + 1 ^ 2}
for the first time
The second time
If the square difference of the distance between the summation point O (0,0), a (C, 0) is constant, the trajectory equation of the point C should be solved in detail. Should we consider who minus whom?
Let such a point be p (x, y), then Po ^ 2 = (x-0) ^ 2 + (y-0) ^ 2 = x ^ 2 + y ^ 2PA ^ 2 = (x-C) ^ 2 + (y-0) ^ 2 = x ^ 2-2cx + C ^ 2 + y ^ 2, so | Po ^ 2-pa ^ 2 | = C | 2cx-c ^ 2 | = square 4C ^ 2x ^ 2-4c ^ 3x + C ^ 4 = C ^ 2. If C = 0, then OA coincides, which is obviously not right, because P is the origin, so C is not equal to 0
Through the ellipse C x ^ 2 / 8 + y ^ 2 / 4 = 1 point P (x0, Y0) to the circle ox ^ 2 + y ^ 2 = 4 lead two tangents PA Pb AB as the tangent point AB and X axis Y axis intersection Mn
1. If the vector PA * vector Pb = 0, find the P coordinate
2. Solving AB equation (expressed by x0, Y0)
3. Find the minimum area of triangle mon
1. Because the meaning vector PA and the vector ob are not zero vectors, so PA ⊥ Pb, so OA ⊥ ob, and because OA = ob, so the quadrilateral OAPB is a square, so Po & sup2; = x0 & sup2; + Y0 & sup2; = 8 ① and the point P is on the ellipse. So x0 & sup2; + 2y0 & sup2; = 8 ② from ① and ②, we get the P (± 2 root) of x0 = ± 2 root sign 2 Y0 = 0
RELATED INFORMATIONS
- 1. The eccentricity of ellipse e: x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1 (a > b > 0) is e, P is the point on e, from P to the circle x ^ 2 + y ^ 2 = B ^ 2, make tangent PA and Pb, a and B are tangent points, Ask if there is a point P, so that PA ⊥ Pb? If there is, calculate the point P coordinate; if not, explain the reason
- 2. It is known that there are two points a (1,3), B (3,0) in the ellipse X225 + y216 = 1, and P is a point on the ellipse, then the maximum value of | PA | + | Pb | is______ ．
- 3. It is proved that the line connecting the two tangent points must pass through a certain point Such as the title
- 4. Given the point Q (2,0) and the circle O: X & # 178; + Y & # 178; = 1, the ratio of the tangent length from the moving point m to the circle to | MQ | is root 2, the trajectory equation of the moving point m is obtained For detailed explanation, please refer to the attached figure,
- 5. Given the point Q (2,0) and the circle C: x2 + y2 = 1 on the rectangular coordinate plane, when the ratio of the tangent length from the moving point m to the circle and MQ is 1 or 2 respectively, the trajectory equation of the point m is obtained
- 6. If the distance between point m and point F (4,0) is less than 1, then the trajectory equation of point m is______ ．
- 7. The distance between two fixed points is 6, and the sum of the squares of the distances from point m to these two fixed points is 26. Find the trajectory equation of point M
- 8. Teacher worldbl: the distance from the moving point m (x, y) to the y-axis is less than the distance from it to the fixed point (2,0). Find the trajectory equation of the moving point m (x, y)
- 9. If the distance from the moving point P to the x-axis is 2 less than the distance to the fixed point F (0,2), then the trajectory equation of the moving point is obtained
- 10. The trajectory equation of a point whose distance from the X axis is equal to 2 is
- 11. In Cartesian coordinates, the distance from the point P (- 1, (√ 3) / 2) to the origin o is
- 12. In Cartesian coordinates, the distance OP from point P (- 2,3) to the origin=______ ．
- 13. In the space rectangular coordinate system, the point a (1,0,2) B (1, - 3, - 1) m is on the Y axis, and the distance to a and B is equal In the space rectangular coordinate system, if the point a (1,0,2) B (1, - 3, - 1) m is on the Y axis and the distances to a and B are equal, then the coordinate of M is?
- 14. Given that the distance from the moving point P to the fixed point F (3,0) and to the fixed value line x = 5 / 2 is constant 2 √ 3 / 3, the trajectory equation of point P is obtained Urgent``
- 15. Two fixed points a (- C, 0), B (C, 0). The sum of the distances from the moving point P to the two fixed points is a constant 2A. Find the trajectory equation of point P
- 16. There are two fixed points a and B in the plane, and | ab | = 2. The ratio of the distance between a moving point m and two points a and B in the plane is 2:1
- 17. The trajectory of a point whose distance from the plane to the fixed point O is equal to 2cm is ()
- 18. Nowadays, there are many devices using batteries as power supply, and the amount of batteries used is very large. Some of them are rechargeable batteries, such as battery car batteries and automobile batteries. These rechargeable batteries all have one feature: the newly purchased batteries can be used for a long time after charging. After long-term use, they will be fully charged, and the power will soon run out. Please use Ohm's law of the whole circuit for analysis! Thank you for your explanation!
- 19. Calculation of maximum power of sliding rheostat by Ohm's law of closed loop If the sliding rheostat is connected in parallel with a resistor, how can the resistor be equivalent to the internal resistance
- 20. Ohm's law of closed circuit Is the terminal voltage necessarily the power supply voltage? What are the internal resistance and external resistance? What are their differences and connections?