百度试题 结果1 题目 7) Find the focal distance of a point on the parabola$$ y ^ { 2 } $$=16x whose ordinate is 2 times the abscissa. 相关知识点: 试题来源: 解析 4 or 8 反馈 收藏
The focal distance of a point on the parabola y^2=16x is 7, then the abscissa of the point is :
PQ is a normal chord of the parabola y2=4ax at P,A being the vertex of the parabola. Through P a line is drawn parallel to AQ meeting the x-axis in R. Then the length of AR is : (A) equal to the length of the latus rectum (B) equal to the focal distance of the point P...
The microwave radiation emitted from the phase-center of a half-wave antenna, located in front of the LHM lens, is first focused on a spot inside the LHM lens and afterwards on point F, at a focal distance f from the interface with the lens. A Comparison between Different Schemes of Mic...
For simplicity, let's say that the hyperbola is centered at0,0with the following foci:Eat−c,0andFatc,0. So, the distance from each focus to the center isc. The distance from a general pointPx,ytoEis given byPE=x−−c2+y−02=x&plus...
This definition of focal radius is usually written c.Usage 2: For other authors, focal radius refers to the distance from a point on a conic section to a focus. In this case the focal radius varies depending where the point is on the curve (unless the conic in question is a circle)....
you will be able to see how Dandelin sphere’s construction works. Just consider a circle and a point outside the circle with label V. If you draw two tangents to the circle at point V, then, you will see that the point of tangency are actually at equal distance from V as shown in...
As you point out, there are advantages to specifying the focal length.. The advantage of knowing the focal ratio is that most aberrations are a function of focal ratio. And relative the field of view relative to the aperture, is determined by focal ratio. ...
Circles drawn on the diameter as focal distance of any point lying on the parabola x^2-4x + 6y + 10 = 0 will touch a fixed line whose equation is
will create a light beam that is wider but travels a shorter distance. On the other hand, positioning a HID lamp shallow into a reflector, meaning that the electric arc is created further from the searchlight's outer lens and closer to the searchlight's ballast, will create a light beam ...