Please do not skip any step solution, and please write the solution step on one piece of paper without use type by using the computer. This is because I scare I will not understand the concept. Thank you very much.

3. Given vectors a = it j+ k, b = i + 2j+ 4k and c = 2i + k. Find (a) the unit vector which is orthogonal to a and b, (b) the angle between a and b. (c) A boat crosses a river with a velocity of 8 km/h. If the resulting velocity of the boat due to the water current is 10 km/h, calculate the velocity of the river water