At the football game, 8 out of every 20 spectators were girls. There were a total of 1560 spectators at the game.
1 answer:
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The diagram of the triangle is missing, so i have attached it.
Answer:
Surface area = 9.425 sq.units
Step-by-step explanation:
When a triangle having an interior angle as 30°, 60° or 90° is rotated, then a cone is formed.
Thus, we need to find the surface area of the cone.
Surface area of a cone is πr ² + πrL
where;
r = radius of the cone
L = slant height of the cone
I have attached the cone formed as the second image.
Looking at the image of the cone, we need to find the radius and slant height.
From the triangle image, we can use trigonometric ratios;
tan 30 = BC/AB
In surd form, BC/AB = 1/√3
Thus, BC is equivalent to 1 and AB equivalent to √3
Using Pythagoras theorem, we can find AC.
(AC)² = (AB)² + (BC)²
AC = √[(AB)² + (BC)²]
AC =√[(√3)² + (1)²]
AC = √[3 + 1]
AC = √4
AC = 2
So, radius, r corresponds to BC = 1
And slant height L corresponds to AC = 2.
Thus,r = 1 and L = 2
So,
Surface area of cone = π(1)² + π(1)(2) = π + 2π = 9.425 sq.units
So I learned this really cool way of finding percents of numbers in my 7th grade math class, hopefully this will help!
In most percent word problems it will have specific wording. For example: What is 25% of 100. Or 75 is 30% of what number? Those are examples of some of the wording (and random numbers) those word problems might use.
The trick is:
so if i have a word problem that says: what IS 15% of 600? here is how your equation would look.
Because you don't know what the "is" is, then you would put x there. If it say 40 is 17% of what? than it would look like this...
To solve just cross multiply or use basic algebra to solve. Using basic algrbra on that last problem I just wrote out would look like this:
In most percent word problems it will have specific wording. For example: What is 25% of 100. Or 75 is 30% of what number? Those are examples of some of the wording (and random numbers) those word problems might use.
The trick is:
so if i have a word problem that says: what IS 15% of 600? here is how your equation would look.
Because you don't know what the "is" is, then you would put x there. If it say 40 is 17% of what? than it would look like this...
To solve just cross multiply or use basic algebra to solve. Using basic algrbra on that last problem I just wrote out would look like this: