question_answer

ABC is a right angled triangle, right angled at C If\[\angle A=60{}^\circ \]and AB = 40 units, then the length of AC is

A)  30                   

B)  20

C)  40                   

D)  None of the above

Correct Answer: B

Solution :

\[\frac{AC}{AB}=\cos 60{}^\circ \] \[AC=AB\cos 60{}^\circ =40\cdot \frac{1}{2}=20\,\,units\]