Answer:
The answer is B.
Step-by-step explanation:
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1 answer:
Answer:
BD = <u>1</u> unit
AD = <u>1</u> unit
AB = <u>1.6</u> units
AC = <u>1.6</u> units
Step-by-step explanation:
In the picture attached, the triangle ABC is shown.
Given that triangle ABC is isosceles, then ∠B = ∠C
∠A + ∠B + ∠C = 180°
36° + 2∠B = 180°
∠B = (180° - 36°)/2
∠B = ∠C = 72°
From Law of Sines:
sin(∠A)/BC = sin(∠B)/AC = sin(∠C)/AB
(Remember that BC is 1 unit long)
AB = AC = sin(72°)/sin(36°) = 1.6
In triangle ABD, ∠B = 72°/2 = 36°, then:
∠A + ∠B + ∠D = 180°
36° + 36° + ∠D = 180°
∠D = 180° - 36° - 36° = 108°
From Law of Sines:
sin(∠A)/BD = sin(∠B)/AD = sin(∠D)/AB
(now ∠A = ∠B)
BD = AD = sin(∠A)*AB/sin(∠D)
BD = AD = sin(36°)*1.6/sin(108°) = 1
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Answer:
2. b : l
3. 20cm
4. 49
5.
Step-by-step explanation:
<u>Solution 2:</u>
Let cylinder is rolled along 'l':
Height of cylinder , h = length of rectangle = l
Perimeter of base = b
Let 'r' be the radius of cylinder's base:
Volume of a cylinder is given as:
Putting the values:
Let cylinder is rolled along 'b':
Height of cylinder , h = length of rectangle = b
Perimeter of base = l
Let 'r' be the radius of cylinder's base:
Volume of a cylinder is given as:
Putting the values:
Taking ratio:
Solution 3:
Rectangle is rolled along its length to make a cylinder, so height will be equal to its length.
height of cylinder = 20 cm
Solution 4:
Side of square = 7 cm
Height of cylinder =Side of square = 7 cm
7 cm will be the circumference of the circle.
i.e. = 7 cm
Curved surface area of a cylinder:
Putting the above values:
CSA = 7 7 = 49
Solution 5:
As calculated in above step:
CSA = 7
7 = 49
Total surface area =
Calculating value of r:
= 7 cm
Total surface area =
Ratio of TSA: CSA is