In a triangle abc, angle C is 90, ab = 18 cm, AC = 9 cm which is equal to angle A.
| February 6, 2021 | education
A right-angled triangle is a triangle in which one of the corners is a straight line (equal to 90 °).
To calculate the value of the angle ∠A, we use the cosine theorem.
The cosine of an acute angle of a right-angled triangle is the ratio of the adjacent leg to the hypotenuse:
cos A = AC / AB;
cos A = 9/18 = 1/2.
1/2 = cos 60º.
Answer: the degree measure of the angle ∠A is equal to 60º; cos A = 1/2.
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