Question

In ΔABC, ∠B = 90°. If AB = 12units and BC = 5units, find: sinA

Answer 1

In ΔABC,
AC² = AB² + BC²
⇒ AC = `sqrt("AB"^2 + "BC"^2)`
⇒ AC = `sqrt(12^2 + 5^2)`
= `sqrt(144 + 25)`
= 13
AB = 12units
BC = 5units
AC = 13units
sin A

= `"Perpendicular"/"Hypotenuse"`

= `"BC"/"AC"`

= `(5)/(13)`.