Question Number 12368 by sin (x) last updated on 20/Apr/17
Answered by mrW1 last updated on 22/Apr/17
$${EF}×\mathrm{cot}\:\mathrm{55}+{EF}×\mathrm{cot}\:\mathrm{35}+\mathrm{4}=\mathrm{10} \\ $$$${EF}×\mathrm{tan}\:\:\mathrm{35}+{EF}×\mathrm{tan}\:\:\mathrm{55}=\mathrm{6} \\ $$$${EF}=\frac{\mathrm{6}}{\mathrm{tan}\:\mathrm{35}+\mathrm{tan}\:\mathrm{55}}=\mathrm{2}.\mathrm{819}\approx\mathrm{3} \\ $$$$\Rightarrow{Answer}\:\boldsymbol{{A}} \\ $$