Objective Mathematics Set-I

1. The lines 3x - 4y + 4 = 0 and 6x - 8y - 7 = 0 are tangents of the same circle. The radius of this circle is
A. 1/2    B. 1/4    C. 3/4    D. 2

2. The three dice are thrown simultaneously, then the probability of getting a score of 7 is
A. 1/6    B. 5/216    C. 1/36    D. none of the above

3. Set A has 3 elements and set B has 4 elements. This number of injections (one to one mapping) that can defined from A to B is
A. 24    B. 144    C. 12    D. none of the above

4. If q is the angle between vectors a and b and | a x b | = | a.b |, then q is equal to
A. 0o    B. 180o    C. 135o    D. 45o