It sounds like <em>R</em> is the region (in polar coordinates)
<em>R</em> = {(<em>r</em>, <em>θ</em>) : 2 ≤ <em>r</em> ≤ 3 and 0 ≤ <em>θ</em> ≤ <em>π</em>/2}
Then the integral is

Answer:
11
Step-by-step explanation:
Let e represent the number of students with blue eyes. Then the number of students with blond hair is 2e. The total number of students is ...
3 + e + 2e -6 = 30
We subtracted 6 because the expressions e and 2e cause the 6 students with both blond hair and blue eyes to be counted twice.
3e = 33 . . . . add 3 and simplify
e = 11
11 students have blue eyes.
Let the legs of the triangle be a and b, and the hypotenuse c.
Your first instinct might tell you to use the Pythagorean theorem to go about solving this because

. This works, but it is slow.
The fastest way to solve this is to recognize that the right triangle is a special triangle where the ratio of the sides are 3:4:5. This means that if the legs are 9 and 12, then the hypotenuse is 15 because 3*3 is 9, 3*4 is 12, and 3*5 is 15.
Answer:
-1
Step-by-step explanation: