A fraternity name formed by two letters would have 24 choices for the first letter, and 24 choices for the second, therefore 24*24=576 is the correct answer.
Answer:
13.2''
Step-by-step explanation:
lets ? be x
x² + 15² = 20²
x² = 20² - 15²
x = √175
x = 13.2''
so missing length = 13.2''
In solving this problem we can consider Earth to be a sphere. When we have a circle, then we can use this formula to find arc length:

Where:
L= arc length (in this problem it is disance we need to travel)
R = radius of circle (in this problem it is equal to a radius of Earth)
C = angle we need to pass
We are told that two cities lie halfway around the world. If we fly to west this means angle is 180°.
This gives an arc length of:

If we want to fly to north we need to go to 90° northern latidtude and then back to 17° latitude. This means angle is:
C=2*(90-17)=2*73°=146°
This gives an arc length of:

We can see that flying north is shorter. It is shorter by:
12440.71 miles - 10090.8 miles = 2349.91 miles
Answer:
B. 45°
Step-by-step explanation:
recall that Thales' theorem states that the diameter of a circle always subtends a right angle on any point on the circle.
what this means is that if ABC is the diameter of the circle, then AD and DC always meet at the circumference at 90°
in this case, if ∠ADC is 90° (by thales theorem), and AD = DC, then we have an isoceles triangle.
This also means that the base angles of the isoceles triangle, ∠DAC and ∠ACD must be equal.
recall that all interior angles of a triangle add up to 180°
180° = ∠ADC + ∠DAC +∠ACD
180° = ∠ADC + 2 ∠ACD
180° = 90° + 2 ∠ACD
2 ∠ACD = 90°
∠ACD = 45°