Are there any numbers that are not included in the real number system?

The trigonometric ratios sine and secant are reciprocals of each other

Look at the hyperbola graphed below. the hyperbola gets very close to the red lines on the graph, but it never touches them. which term describes each of the red lines? o o o o a. asymptote b. directrix c. focus d. axis

Which expression demonstrates the use of the commutative property of addition in the first step of simplifying the expression (-1+i)+(21+5i)+0