An irrational number is one with a fraction.
Sin angle that equals the 1/2 value is the 30 degree on the 1st Quadrant.
The angle of 30 degree on the 3rd Quadrant is equivalent to (formula and circle in the 1st photo) 180 + 30 = 210°.
So theta = 210° (3rd Quadrant) = 30° (1st Quadrant).

Now just transfer the cos 30° to the 3rd Quadrant and the signal will be negative (as shown in the 2nd photo attached).
Answer:
$25 - $10f
Step-by-step explanation:
Fishie's name is fishy.
We know Mr. Fishie spent $15 on a tank. His 10 fish cost 10*$f. His total is:
Total =15 + 10*f
His change after 2 $20 would be:
$40 - ($15 - $10f), or
$25 - $10f
Total is just add
n+16 is total of 16 and n