Describe the cross-section form by the intersection of the plain and solid

What is the length of the unknown leg in the right triangle ?

What is not true about kl and mn? what is mn? (show )

What is the probability of throwing several dice with sum equal to 6 (six)? show the ways of possibilities for sum 6 (as the numerator) and the ways of throwing n dices for n = 1, 2, 3, 4 or 5 as denominator for all the questions to earn full credits. (a)throw one die, (b) throw two dice, (c) throw three dice (d) throw 4 dice, (e) throw 5 dice