Answer:

Step-by-step explanation:
The total surface area of a cone is given by :

Put r = 2r and l = 2l in the above formula

Hence, the total surface area of the cone is
.
Answer:
YZ = XZ
Step-by-step explanation:
Perpendicular Bisector:
A perpendicular bisector of a line segment 'l' is a line that is perpendicular to the line segment 'l' and cuts the line segment 'l' into two equal parts.
Given:
1. A triangle WXY.
2. A perpendicular bisector from vertex W that intersects XY at point Z.
Conclusion based on the drawing:
a. Z is the midpoint of the line segment XY because point Z lies on the perpendicular bisector of XY.
b. Hence, XZ = YZ.
Answer:
"The mean is the average of the numbers: a calculated "central" value of a set of numbers. To calculate it: add up all the numbers, then divide by how many numbers there are." -- Math is Fun
Answer:
80 + 18i
Step-by-step explanation:
i² = -1
x = i + 9
x² = (i + 9)²
Applying; (a + b)² = a² + 2ab + b² concept,
x² = i² + 18i + 81
We know that i² = -1
So x² = -1 + 18i + 81
x² = 81 - 1 + 18i = 80 + 18i
Answer:
yes
Step-by-step explanation:
10 20 30 40 50 60 70 80 90 100 etc