Review the proof (not in order) of the identity tan(0/2) = + √1-cos(0)/1+cos(0) which is the correct sequence of steps

Select the correct answer. in the figure, angle k measures 45°. what is the measurement of angle c? a. 38° b. 45° c. 90° d. 98°

Can someone me with this problem . show your work .

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis. 3- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in part b?