The radius of a circle circumscribed about a triangle is 10 cm. Find the side of the triangle

The radius of a circle circumscribed about a triangle is 10 cm. Find the side of the triangle that lies opposite an angle of 30 degrees.

The side AB of triangle ABC in a circle is a chord. The length of the chord L can be calculated by the formula

L = 2 * R * sin (<AOB / 2); <AOB – center angle;

<AOB = 2 * <ACB, since <ACB is an inscribed angle based on the same arc as <AOB;

<AOB = 2 * 30 ° = 60 °;

L = 2 * R * sin (60 ° / 2) = 2 * R * sin 30 °;

sin 30 ° = 0.5;

L = 2 * 10 * 0.5 = 10 (cm).



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.