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Category: Geometry

Question-35763

Question Number 35763 by $@ty@m last updated on 23/May/18 Answered by ajfour last updated on 23/May/18 $${let}\:\angle{BDF}\:=\:\alpha \\ $$$${AF}=\mathrm{30cos}\:{A}\:\:;\:\:\:{AE}=\mathrm{36cos}\:{A} \\ $$$$\mathrm{cot}\:\alpha\:=\:\frac{{AF}\mathrm{cos}\:{B}+{AE}\mathrm{cos}\:{C}}{{BF}\mathrm{sin}\:{B}−{CE}\mathrm{sin}\:{C}} \\ $$$$\:\:\:=\frac{\mathrm{30cos}\:{A}\mathrm{cos}\:{B}+\mathrm{36cos}\:{A}\mathrm{cos}\:{C}}{\left(\mathrm{18}−\mathrm{30cos}\:{A}\right)\mathrm{sin}\:{B}−\left(\mathrm{15}−\mathrm{36cos}\:{A}\right)\mathrm{sin}\:{C}} \\ $$$${BD}={BF}\mathrm{cos}\:{B}+{BF}\mathrm{sin}\:{B}\mathrm{cot}\:\alpha…

Question-35750

Question Number 35750 by ajfour last updated on 23/May/18 Commented by ajfour last updated on 23/May/18 $${Find}\:{proportion}\:{of}\:{blue},\:{brown}, \\ $$$${yellow},\:{and}\:{red}\:{coloured}\:{areas}. \\ $$$${Given}:\:{chord}\:{makes}\:{angle}\:\theta\:{with} \\ $$$${the}\:{diameter}\:{shown}\:{and}\:{that}\:{the} \\ $$$${point}\:{of}\:{intersection}\:{of}\:{the}\:{chord}…

Question-166676

Question Number 166676 by ajfour last updated on 24/Feb/22 Answered by ajfour last updated on 24/Feb/22 $${R}\mathrm{sin}\:\theta+\mathrm{2}{r}={R} \\ $$$$\mathrm{sin}\:\theta=\frac{{r}}{{R}−{r}} \\ $$$$\Rightarrow\:\:{Rr}=\left({R}−\mathrm{2}{r}\right)\left({R}−{r}\right) \\ $$$$\Rightarrow\:\:{R}^{\mathrm{2}} −\mathrm{4}{rR}+\mathrm{2}{r}^{\mathrm{2}} =\mathrm{0}…