Question

Решите: 1)ctg(-225) 2)sin(-150) 3)tg(-225) 4)cos 120 Заранее спасибо

Answer 1

-ctg(225)=-ctg(180+45)=ctg(45)=1
sin(-150)=-sin(150)=-sin(180-30)=-sin(30)=-1/2
tg(-225)=tg(180+45)=tg(45)=1
cos 120 =-sin(90+30)=-sin30=-1/2
Здесь работают формулы приведения

Answer 2

Calculation Results:

1) ctg(-225): To calculate the cotangent of -225 degrees, we can use the identity that cot(x) = 1/tan(x). Therefore, ctg(-225) = 1/tan(-225).

Using a calculator or a trigonometric table, we find that tan(-225) is equal to -1. So, ctg(-225) = 1/(-1) = -1.

2) sin(-150): To calculate the sine of -150 degrees, we can use the fact that sin(x) = -sin(-x). Therefore, sin(-150) = -sin(150).

Using a calculator or a trigonometric table, we find that sin(150) is equal to 0.5. So, sin(-150) = -0.5.

3) tg(-225): To calculate the tangent of -225 degrees, we can use the identity that tan(x) = sin(x)/cos(x). Therefore, tg(-225) = sin(-225)/cos(-225).

Using a calculator or a trigonometric table, we find that sin(-225) is equal to -0.7071 and cos(-225) is equal to 0.7071. So, tg(-225) = (-0.7071)/(0.7071) = -1.

4) cos(120): To calculate the cosine of 120 degrees, we can use a calculator or a trigonometric table. The cosine of 120 degrees is equal to -0.5.

Therefore, cos(120) = -0.5.

Please note that the calculations provided above are based on the trigonometric identities and values obtained from a calculator or a trigonometric table.