Practice problem
Given sin(a)=23\sin(a)=\frac23sin(a)=32 and cos(b)=−14\cos(b)=-\frac14cos(b)=−41, with aaa and bbb both in the interval [π2,π)[\frac{\pi}2,\pi)[2π,π) find cos(a−b)\cos(a-b)cos(a−b).
−5+21512-\frac{\sqrt{5}+2\sqrt{15}}{12}−125+215
5+21512\frac{\sqrt{5}+2\sqrt{15}}{12}125+215
−3+4512-\frac{\sqrt{3}+4\sqrt{5}}{12}−123+45
3+4512\frac{\sqrt{3}+4\sqrt{5}}{12}123+45
Type a concept, like “slope” or “photosynthesis”.