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______ ．

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______ ．

The elliptical equation is X225 + y2216 = 1, and the focal coordinate is B (3,0) and B '(- 3,0) connecting PB' and ab ', and connecting PB' and ab '(- 3,0) connecting PB' and ab '. According to the definition of ellipse, we can get pb| + | PB' | PB '| PB' | PB '| 124\124\\\\\\124\124\124124\\124\124\\\124\\i'm sorry

How to prove that the length of two tangent lines leading from a point outside the circle is equal, and the angle between the two tangent lines is bisected by the line connecting the center of the circle and this point?

Two tangents of a circle from a point outside the circle have the same length, and the line between the center of the circle and this point bisects the angle between the two tangents

How to prove that a line is tangent to a circle
It seems that there are two ways. One is to know that a point is on a circle, that is to prove that the line between the point and the center of the circle is perpendicular to the straight line, and the other is to forget

1. Prove perpendicularity with radius (tell point on circle)
2. Make a vertical line and prove that the length from the point to the center of the circle is the radius