Using trig ratios to find the missing side or angle of a right triangle
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[tex]\\ \sf\longmapsto cos31=\dfrac{12}{x}[/tex]
[tex]\\ \sf\longmapsto 0.85=\dfrac{12}{x}[/tex]
[tex]\\ \sf\longmapsto x=\dfrac{12}{0.85}[/tex]
[tex]\\ \sf\longmapsto x=14.11[/tex]
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[tex] \: [/tex]
cos (31°) = 12/x
0.85 = 12/x
x = 12/0.85
x ≈ 14.1