If the line joining the points `(x_1,y_1)` and `(x_1,y_1)` subtends a right angle at the point `(1,1)` then

If the line joining the points (_x_1, y_1) and (x_2, y_2) subtends a right angle at the point (1,1), then x_1 + x_2 + y_2 + y_2 is equal to

If the line joining the points (-x_(1),y_(1)) and (x_(2),y_(2)) subtends a right angle at the point (1,1), then x_(1)+x_(2)+y_(2)+y_(2) is equal to

If the line segment joining the points P(x_1, y_1)a n d Q(x_2, y_2) subtends an angle alpha at the origin O, prove that : O PdotO Q cosalpha=x_1x_2+y_1y_2dot

If the line segment joining the points P(x_1, y_1)a n d\ Q(x_2, y_2) subtends an angle alpha at the origin O, prove that : O PdotO Q\ cosalpha=x_1x_2+y_1y_2dot

If the line - segment joining the points A(x_(1),y_(1))andB(x_(2),y_(2)) subtends an angle alpha at the origin O, then find the value of cosalpha .

The line join of the points (2,3) and (-1,5) subtends a right angle at P. If the locus of P is a circle then its radius is

A line joining the points (1,1,1) and (2,2,2) intersect the plane x+y+z=9 at the point

If the chord joining the points (1,-3),(-3,1) subtends a right angle at the centre of the circle,then equation of the circle is

If the chord joining the points (2,-1),(1,-2) subtends a right angle at the centre of the circle,then its centre and radius are

If theta\ is the angle which the straight line joining the points (x_1, y_1)a n d\ (x_2, y_2) subtends at the origin, prove that tantheta=(x_2y_1-x_1y_2)/(x_1x_2+y_1y_2)\ a n dcostheta=(x_1x_2+y_1y_2)/(sqrt(x1 2+y1 2x2 2+y2 2))