21. Number of ways in which three distinct numbers can be selected between 1 and 20 both inclusive, whose sum is even is_ 22. A circle passes through the points (2, 2) and (9, 9) and touches the x-axis. The absolute value of the difference of possible x-coordinate of the point of contact is If a, b are any two perpendicular vectors of equal magnitude and 3 +4b|+|4a-35|=20, then a equals: 24. The value of dx is equal to where a, b are co-prime numbers, then a.b is b 25. lim aex-bcosx+c x->0 xsin x =1, then a+b+c is equal to usha