Question

In an isosceles triangle ABC, AB = BC = 6 cm and ∠B = 90°. Find the values of cos C

Answer 1

ΔABC is an isosceles right-angled triangle.
∴ AC²
= AB² + BC²
= 6² + 6²
= 36 + 36
= 72
⇒ AC = `6sqrt(2)"cm"`
cos C 

= `"BC"/"AC"`

= `(6)/(6sqrt(2)`

= `(1)/sqrt(2)`.