0\\\\cos300^0=cos(270^0+30^0)\in 4\; chetvert\; \to \; cos300^0>0\\\\sin100^0\cdot cos300^0>0" alt="sin100^0=sin(90^0+10^0)\in 2\; chetvert\; \to \; sin100^0>0\\\\cos300^0=cos(270^0+30^0)\in 4\; chetvert\; \to \; cos300^0>0\\\\sin100^0\cdot cos300^0>0" align="absmiddle" class="latex-formula">