Question

)arccos(-0.8) ; arccos п/4 ; arccos0.6 ; 2)arctg 21 ; arctg 8.9 ; arctg (-30) ;

Answer 1

1) arccos(-0.8) ; arccos п/4 ; arccos0.6

2) arctg 21; arctg 8.9; arctg (-30)

в порядке возрастания

Answer 2

Let's calculate the values of the given trigonometric expressions:

1. $\arccos(-0.8)$: $\arccos(-0.8)$ is the inverse cosine of -0.8. To find this value, you can use a calculator or a mathematical software:

   $\arccos(-0.8) \approx 2.4981$ radians (in radians).

2. $\arccos(\pi/4)$: $\arccos(\pi/4)$ is the inverse cosine of $\pi/4$. To find this value, you can use a calculator or a mathematical software:

   $\arccos(\pi/4) \approx 0.9033$ radians (in radians).

3. $\arccos(0.6)$: $\arccos(0.6)$ is the inverse cosine of 0.6. To find this value:

   $\arccos(0.6) \approx 0.9273$ radians (in radians).

4. $\arctan(21)$: $\arctan(21)$ is the arctangent of 21. To find this value, you can use a calculator or a mathematical software:

   $\arctan(21) \approx 1.5208$ radians (in radians).

5. $\arctan(8.9)$: $\arctan(8.9)$ is the arctangent of 8.9. To find this value:

   $\arctan(8.9) \approx 1.4739$ radians (in radians).

6. $\arctan(-30)$: $\arctan(-30)$ is the arctangent of -30. To find this value:

   $\arctan(-30) \approx -1.5375$ radians (in radians).

These values are approximate and are given in radians. If you need them in degrees, you can convert them by multiplying by $\frac{180}{\pi}$ since there are approximately $180$ degrees in $\pi$ radians.