Answer: 135cm
Step-by-step explanation
Volume of a cylinder = πr²h
Volume of a cone. = 1/3πr²h
The two shapes are both solid shapes.
Since the have same volume, we can then equate the two together and solve for the height of the cone.
Now make H the height and R the radius of the cylinder and h the height and r the radius of the cylinder.
Now equating the two
πR²H = 1/3πr²h
Now substitute for the values now
Multiply through by 3
3πR²H = πr²h
But π is common so it could be obliterated from the equation
3R²H = r²h
3 x 12² x 20 = 8² x h
3 x 144 x 20 = 64 x h
60 x 144 = 64h
8640. = 64h
Therefore
h = 8640/64
= 135cm
Answer:
B.
Step-by-step explanation:
The ratio of the lengths of the sides of a 30-60-90 triangle is
1 : sqrt(3) : 2
From the 1 and 2, we see that the hypotenuse must be twice the length of the short leg.
From the 1 and sqrt(3) we see that the long leg is sqrt(3) times the length of the short leg.
Now we check for these two ratios in each choice.
A.
1 is twice 1/2. Check
sqrt(3)/2 is sqrt(3) times 2. Check
B.
10 is twice 5, not twice 5/2. This does not check.
C.
2sqrt(2) is twice sqrt(2). Check
sqrt(6) is 2sqrt(2) time sqrt(3). Check
D.
6 is twice 3. Check
3sqrt(3) is sqrt(3) times 3. Check
Answer: B.
(- 1 + √3)/2
rationalise the denominator by multiplying the numerator/denominator by the conjugate of the denominator.
the conjugate of 1 + √3 is 1 - √3
(1 - √3)/(1 + √3)(1 - √3) = (1 - √3)/( 1² - (√3)²) = (1 - √3)/(1 - 3) = (1 - √3)/(- 2)
multiply numerator/denominator by (- 1)
=(-1 +√3)/2
