How many degrees does she rotate the telescope to see star b?

We have to use the law of cosines to solve for the missing angle.

cos(?) = (400^2 + 450^2 - 90^2) / (2*400*450).

Since, we want the exact value, we are going to take the inverse cosine of both sides

? = 10 degrees

The astronomer had to rotate her telescope 10 degrees to see star B

x > 1.3

step by step:

8.5−0.9x> 9.8−1.9x

step 1: simplify both sides of the inequality.

−0.9x+8.5> −1.9x+9.8

step 2: add 1.9x to both sides.

−0.9x+8.5+1.9x> −1.9x+9.8+1.9x

1x+8.5> 9.8

step 3: subtract 8.5 from both sides.

1x+8.5−8.5> 9.8−8.5

1x> 1.3

step 4: divide both sides by 1.

1x/1 > 1.3/1