4. Suppose the reciprocal (1) button on a calculator is broken. Assume division and, more broadly, arithmetic operations keys don't work, ei- ther. Keys to enter numbers, including decimals (.) and signed numbers (+/-), do work. Show how the reciprocal of any nonzero real number z can be com- puted using some combination of a calculator's trigonometry keys, namely: sin, cos, tan, sin-, cos, tan-