Hydraglass I’d be willing to wager no one in this chat knows what the COS(pi/5) * SIN (pi/3) is nor would they be able to without a calculator.
You’d be wrong. The trig identities to solve that are high school stuff, and my al/geo teacher wouldn’t let us use calculators at all. In Mr. F’s words, “I want the exact answer. A calculator won’t give you that.”
(and at the time it was true - my calculator had constants for pi, e, and about 40 other transcendental constants that get used in physics, but it would always try to do a decimal approximation rather than spit out a rational answer)