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...
The distance from a general pointPx,ytoEis given byPE=x−−c2+y−02=x+c2+y2. The distance fromPtoFis given byPF=x−c2+y−02=x−c2+y2. Looking at the case in whichPis a vertex of the hyperbola and subtracting t...
1、Focal point is, the distance between the two is the focus of the focal length.定点是焦点,两焦点的距离是焦距。 2、Dead.I don't know why he chose me as the focal point of his anger.我不明白他为什么选择我做他怒气的宣泄中心。 3、The focal point of this topic is the system design ...
Usage 2: For other authors, focal radius refers to the distance from apointon aconic sectionto a focus. In this case the focal radius varies depending where the point is on thecurve(unless the conic in question is acircle). If there are two foci then there are two focal radii. ...
The property of an ellipse or hyperbola whereby lines drawn from the foci to any point on the conic make equal angles with the tangent to the conic at that point. The property of a parabola whereby a line from the focus to any point on the parabola, and a line through this point paral...
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. ...
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 ...