ΔABC is right angled at C with sides AB = 10 cm and AC = 6 cm. Find Cos(∠B).
45
In ΔABC,AB=10 cm,AC=6 cm
Applying Pythagoras theorem to δABC, we have
AC2+BC2=AB2
62+BC2=102
⟹BC2=100−36
⟹BC=√64=8 cm
The cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse.
∴cos(∠B)=BCAB=810=45