The common difference, d, can be determined by subtracting the two consecutive values:
1 - 5 = -4
-3 - 1 = -4
-7 - -3 = -4
Then, using the equation:
an = a1+ d(n-1)
a_21 = 5 + (-4)(21 - 1)
a_21 = -75
The answer is letter D. I hope I was able to help you. Have a good day!
Answer:
C. 18 cm
Step-by-step explanation:
The ratio of the sides of the triangle shown is 12 : 15 = 4 : 5. We know it is a right triangle, so we know the missing side length completes the ratio
3 : 4 : 5 = 9 : 12 : 15
Half of XY is 9 cm, so the length of the entire chord is 18 cm.
_____
The chord is tangent to the inner circle, so makes a 90° angle with the radius to that tangent point. This tells you that the triangle shown is a right triangle. It also tells you that the short radius bisects the chord. The Pythagorean theorem can be used to find the length of the side not shown (half the chord length).
The unknown side (a) can be found from ...
15² = 12² +a²
225 -144 = a² . . . . . . subtract 12²
81 = a² . . . . . . . . . . . simplify
9 = a . . . . . . . . . . . . . take the square root
The chord length is 2a, so is ...
2(9 cm) = 18 cm . . . . length of chord XY
If there are four choices it is 3/4
Answer and Step-by-step explanation:
First, solve for the volume of the sphere, then solve for the height of the cone using the volume of the sphere (which is said to be equal to the volume of the cone) and the radius given.
<u>Volume formula of Sphere</u>
V = 
<u>Substitute 1 in for r</u>
= Volume
<u>Finding the Height of a Cone</u>
Volume formula for Cone: 
<u />
<u>Solve for </u><u><em>h</em></u>
Multiply both sides by 3, then divide by pi and r^2.
<u>Plug in the volume and the radius.</u>
<u>Simplify</u>
h ≈ 4
<u>4 is approximately the height.</u>
<u></u>
<u></u>
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