Answer:
28π cm²
Step-by-step explanation:
The surface of a cylinder is given by the formula:
where r is the radius of the base, and h is the height.
Using the image, we can find that the radius of the cylinder would be 2 cm, and the height would be 5 cm.
Now, to find the surface area of the cylinder, we would have to plug in 2 for r (the radius of the base) and 5 for h (the height of the cylinder) into the formula for the surface area of a cylinder.
Now we plug in 2 for r and 5 for h for the equation for the surface area of a cylinder:
2π(2)(5) + 2π(2)² = 20π + 2π(4) = 20π + 8π = 28π
Remember, the radius and the height are given to us in cm, and w are solving for surface area, so the answer should be in cm² (square centimeters).
The surface area of the cylinder would be 28π cm².
28π cm² would be an exact answer. For the approximate answer, plug in 3.14 (most math classes use 3.14 to approximate π) for π.
I hope you find this helpful. :)
Answer:
If AB is a tangent to the circle, the triangle ABO is right angled, as the angle where a tangent meets the circumference is always 90 degrees.
We also know that Pythogoras' theorem only holds for right angled triangles.
The hypotenuse is 12 + 8 as 12 is the radius so is 20.
16^2+12^2 = 256 + 144 = 400 = 20^2 so AB must be tangent.
Answer:
A) -2 - i√3 , -2 + i√3
Step-by-step explanation:
Solve using quadratic formula
x² + 4x + 7 = 0
The Almighty Formula
= -b ± √b² - 4ac/2a
Where ax + bx² + c = 0
From the above question
a = 1, b = 4, c= 7
Hence,
-4 ± √4² - 4 × 1 × 7/2 × 1
-4 ± √16 - 28/2
=( -4 ± √-12)/2
Since
b² - 4ac < 0
We have two complex roots
Simplifying
( -4 ± √-12)/2
= -4/2 ± √-12/2
= -2 ± 2√3i/2
= -2 ± √3i
Therefore,
-2 - √3i , -2 + √3i
or
-2 - i√3 , -2 + i√3
Option A , is the correct answer
