Question

In ΔABC, ∠A = 90°. If AB = 5 units and AC = 12 units, find: cos C

Answer 1

In ΔABC,
BC² = AB² + AC²
⇒ BC = `sqrt("AB"^2 + "AC"^2)`
⇒ BC = `sqrt(5^2 + 12^2)`
= `sqrt(169)`
= 13
AC = 12 units
BC = 13units
AB = 5units
cos C

= `"Base"/"Hypotenuse"`

= `"AC"/"BC"`

= `(12)/(13)`.