The probability of picking a black ball first is

, because there are 4 black balls and 1 white ball which is 5 balls in total. After picking the first ball, 4 balls remain - 3 black and 1 white, so the probability of picking a white ball is

.
So, the probability of picking a black ball first followed by a white ball is
Hi, It is simple:
Sin(A) = a / c
Cos(A) = b / c
Tan(B) = b / a
Sin(J) = j / i
Cos(K) = j / i
Tan(K) = k / j
This are the answers