Question

Answer 1

\(\left(sina+cosa\right)^2=1,366^2\)

\(\Leftrightarrow sin^2a+cos^2a+2sina.cosa=1,366^2\)

\(\Rightarrow sina.cosa=\dfrac{1,366^2-1}{2}\)

\(tana+cota=\dfrac{sina}{cosa}+\dfrac{cosa}{sina}=\dfrac{sin^2a+cos^2a}{sina.cosa}=\dfrac{1}{sina.cosa}=\dfrac{2}{1,366^2-1}\)

\(D=\left(tana+cota\right)^3-3tana.cota\left(tana+cota\right)\)

\(=\left(\dfrac{1}{sina.cosa}\right)^3-\dfrac{3}{sina.cosa}=\left(\dfrac{2}{1,366^2-1}\right)^3-\dfrac{6}{1,366^2-1}=...\)