The formulas

serve to define the basic complex trigonometric functions. Write out the formulas for their real and imaginary parts in terms of z = x + i y. and show that cos z and sin z reduce to their usual real forms when z = a- is real. What do they become when z = i y is purely imaginary?

Transcribed Image Text:

:" + e-に iz e-e-iz 2i cos z and sin z -