Question

Cos a = -4/5 П/2<а<П Найти sin a

Answer 1

Sin a= sqrt(1-16/25)=sqrt(9/25)=3/5
Т.к. угол лежит на промежутке от П/2 до П, то минус этого угла положительный

Ответ: 3/5 или 0,6

Answer 2

To find the value of sin(a), we first need to determine the quadrant in which the angle "a" lies. The given interval for "a" is π/2 < a < π. In this range, a lies in the second quadrant where the sine function is positive.

Since the sine function is positive in the second quadrant, we can use the following trigonometric identity:

sin(a) = √(1 - cos²(a))

where cos(a) = -4/5 (as given).

Let's calculate sin(a):

sin(a) = √(1 - cos²(a)) sin(a) = √(1 - (-4/5)²) sin(a) = √(1 - 16/25) sin(a) = √(9/25) sin(a) = 3/5

Therefore, the value of sin(a) is 3/5.