In an obtuse triangle ABC AC = BC = 25, the height AH is 20. Find cosACB.
March 15, 2021 | education
| In a right-angled triangle ACН, according to the Pythagorean theorem, we determine the length of the leg CH.
CH ^ 2 = AC ^ 2 – AH ^ 2 = 625 – 400 = 225.
CH = 15 cm.
Determine the cosine of the ACН angle.
CosАСН = СН / АС = 15/25 = 0.6.
Angles АСН and АСВ are adjacent angles, then CosACВ = -CosАCH = -0.6.
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.