2 x 955.49 tg. x 2 + 100 = Cosec. x {\displaystyle 2{\text{ }}{\text{ x }}955.49{\text{ tg. }}{\frac {x}{2}}+100={\text{ Cosec. }}x}
955.49 tg. x 2 + 50 = 100 Cosec. x {\displaystyle 955.49{\text{ tg. }}{\frac {x}{2}}+50=100{\text{ Cosec. }}x}
191.098 tg. x 2 + 10 = 20 2 Sin. x 2 Cos. x 2 = 10 Sin. x 2 Cos. x 2 {\displaystyle 191.098{\text{ tg. }}{\frac {x}{2}}+10={\frac {20}{2{\text{ Sin. }}{\frac {x}{2}}{\text{ Cos. }}{\frac {x}{2}}}}={\frac {10}{{\text{ Sin. }}{\frac {x}{2}}{\text{ Cos. }}{\frac {x}{2}}}}}
191.098 Sin. x 2 Cos. x 2 + 10 = 10 Sin. x 2 Cos. x 2 {\displaystyle 191.098{\text{ }}{\frac {{\text{ Sin. }}{\frac {x}{2}}}{{\text{ Cos. }}{\frac {x}{2}}}}+10={\frac {10}{{\text{ Sin. }}{\frac {x}{2}}{\text{ Cos. }}{\frac {x}{2}}}}}
191.098 Sin. 2 x 2 + 10 Sin. x 2 Cos. x 2 = 10 {\displaystyle 191.098{\text{ }}{\text{ Sin.}}^{2}{\frac {x}{2}}+10{\text{ Sin. }}{\frac {x}{2}}{\text{ Cos. }}{\frac {x}{2}}=10}
191.098 ( 1 − Cos. x ) + 20 Sin. x 2 Cos. x 2 = 20 {\displaystyle 191.098{\text{ }}(1-{\text{ Cos. }}x)+20{\text{ Sin. }}{\frac {x}{2}}{\text{ Cos. }}{\frac {x}{2}}=20}
191.098 ( 1 − Cos. x ) 10 Sin. x = 20 {\displaystyle 191.098{\text{ }}(1-{\text{ Cos. }}x)10{\text{ Sin. }}x=20}
191.098 − 191.098 Cos. x + 10 Sin. x = 20 {\displaystyle 191.098-191.098{\text{ Cos. }}x+10{\text{ Sin. }}x=20}
On obtient : x = 23 ∘ 36 ′ 32.9 ″ {\displaystyle x=23^{\circ }36'32.9''}
On trouve facilement A C {\displaystyle AC} et C B {\displaystyle CB} .
A C = 955.49 tg. 23 ∘ 36 ′ 32.9 ″ 2 = 199.691 pieds {\displaystyle AC=955.49{\text{ tg. }}{\frac {23^{\circ }36'32.9''}{2}}=199.691{\text{ pieds}}}
C D = 2 x 199.691 + 100 = 499.382 pieds {\displaystyle CD=2{\text{ }}{\text{ x }}199.691+100=499.382{\text{ pieds}}}
Vérification : 499.382 x sin. 23 ∘ 36 ′ 32.9 ″ = 200 {\displaystyle 499.382{\text{ }}{\text{ x sin. }}23^{\circ }36'32.9''=200}
A B = C D Cos. 23 ∘ 36 ′ 32.9 ″ + 2 A C = 499.382 Cos. 23 ∘ 36 ′ 32.9 ″ + 399.382 = 457.58 + 399.382 = 856.962 {\displaystyle {\begin{array}{rl}AB&=CD{\text{ Cos. }}23^{\circ }36'32.9''+2{\text{ }}AC\\&=499.382{\text{ Cos. }}23^{\circ }36'32.9''+399.382\\&=457.58+399.382\\&=856.962\end{array}}}