Planes M and N intersect at line d. Line a forms a right angle with line d. Line b is diagonal and crosses line d. Line c is on plane N and is diagonal. Line e is on plane M and is slightly diagonal at the top of the plane. Which are skew lines? Check all that apply.

a and b
c and b
b and e
e and c
a and e
a and c

Which of the following statements is true? a. the irrational number system is not closed under multiplication, because the product of two irrational numbers is always a rational number. b. the irrational number system is not closed under multiplication, because the product of two irrational numbers is not always an irrational number. c. the irrational number system is closed under multiplication, because the product of two irrational numbers is always an irrational number. d. the irrational number system is closed under multiplication, because the product of two irrational numbers is always a rational numbers. reset submit