# In the triangle ABC AC = BC, AB = 5, BH – height, AH = 3. Find cos B.

September 14, 2021 | education

| Since ВН is the height of the ABC triangle, the ABН triangle is rectangular.

In a right-angled triangle, the cosine of an acute angle is the ratio of the adjacent leg to the hypotenuse.

CosBAH = AH / AB = 3/5.

Since, by condition, AC = BC, then the triangle ABC is isosceles, and then the angle CAB = CBA, and hence CosCBA = CosCAB = 3/5.

Answer: The cosine of angle B is 3/5.

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.