Question

Найдите sin, если соs=и 270°<а<360°​

Answer 1

Ответ:-0,4;

Объяснение:

sin²a+cos²a=1 - основное тригонометрическое тождество

sin²a+(√21/5)²=1

sin²a+21/25=1

sin²a=1-21/25

sin²a=4/25

sina=±√4/25

sina=±2/5

sina=±0,4

Так как sina в  270°<а<360°т.е в 4 четверти отрицателен, то

sina=-0,4;

Ответ;sina=-0,4;

Answer 2

To find the value of sin given that cos is in the range of 270° < a < 360°, we can use the trigonometric identity: sin^2(a) + cos^2(a) = 1.

Since cos(a) = -1 at 270° < a < 360°, we can substitute this value into the identity and solve for sin(a):

sin^2(a) + (-1)^2 = 1 sin^2(a) + 1 = 1 sin^2(a) = 0 sin(a) = 0

Therefore, sin(a) = 0 when 270° < a < 360°.