In a triangle ABC, the angle is C = 90∘, ∠B = 30∘, AB = 10. Find the length of the side AC.

According to the condition of the problem △ ABC rectangular, AB hypotenuse, AC and BC legs. The AC / AB ratio is sine ∠B by definition of sine.

By the condition of the problem, we know the value ∠B. According to the sine table sin 30 ° = 1/2.


AC / AB = 1/2;

AC = 1/2 * AB = 1/2 * 10 = 5.

Answer: 5.

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