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Posts tagged with sine

Math Jokes – you either love them or h8 them!

September26
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Trig Ratios Unplugged

May31

Sine, Cosine and Tangent are the three main trigonometric or Trig Ratios. Before we look at these in more detail, where did these strange terms come from? Trigonometric functions were studied by Hipparchus of Nicaea (180–125 BC), Ptolemy of Egypt (90–165 AD), Aryabhata (476–550), Varahamihira, Brahmagupta, Ulugh Beg and others (14th century). The word “sine” […]

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Riding the Sine Wave…

December8

A sine wave is a repetitive change or motion which, when plotted as a graph, has the same shape as the sine function. For example, on the right is a weight suspended by a spring. As it bounces up and down, its motion, when graphed over time, is a sine wave. In reality, friction and […]

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Sound Waves and Noise Cancelling

July21

Play the note A Play the (shifted) note A You may have seen advertisements for “noise reducing” headphones. Here’s a rough idea of how they work. First they figure out what kind of noise is reaching your ears. Essentially this means it figures out the sine waves of the ambient sounds. Then it creates additional […]

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Sine Method used to measure tallest tree

January23

Scientists recently measured the tallest tree in New Zealand at just over 81 metres. How did they do this? Using lasers and the Sine method – that is, the Sine of the angle formed by the lasers gave the height/hypotenuse. Read more here. (Note: This image is not of the tallest tree but gives some […]

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Trig Ratios – Part 2

August9

Look at the following equations and see if you can find the mathematical pattern; Sin 30 = 0.5 Cos 60 = 0.5 Sin 60 = 0.866 Cos 30 = 0.866 Sin 0    = 0 Cos 90 = 0 Sin 45 = 0.707 Cos 45 = 0.707 Sin 80 = 0.985 Cos 10 = 0.985 […]

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Hear Ye, Hear Ye, Math = Sound Waves!

July4

There is a lot of information on the web about sound waves and the mathematical patterns surrounding them. For example, the changes in air pressure produce sine curves such as this one below. Of course, there are complex formulae that apply in calculating sound effects. When we listen to a radio or TV we hear […]

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Post Support

Largest number between o and 1 million which does not contain the ‘n’ is 88

 

Rotation SAT Problem: Answer: 4 (see: https://www.youtube.com/watch?v=FUHkTs-Ipfg)

 

Which number has its letters in alphabetical order? Answer: F O R T Y

Hidden Rabbit? Clue: check the trees

How long for the stadium to fill? 45 minutes.

Where are you? the North Pole

Prize Object Puzzle: If Sue does not know where the prize is in the first question, it can’t be under the square. She must have been told it is under another shape. Apply this same logic to Colin. It is then obvious that the prize cannot be under a yellow object. That helps Sue eliminate her yellow shapes. Got the idea?

Algebra Puzzle: Answer = 1

Popular Math Problems Answers: 1, 1

Number of tabs? According to Lifehacker, the ideal number of tabs you should have open is nine. Yes, a single digit. To some, this is like playing a piano and only using a fraction of the notes!

Worst Graph? Where to start. What a visual mess and even some of the lines merge and are impossible to follow. A graph is a visual display of data, with the goal to identify trends or patterns. This is a spider’s web of information which fails to show a clear pattern at all. Solution? Well, different colors would help, or why not group in two or three graphs where trends are similar?

Number of different nets to make a cube is eleven – see this link

Homework Puzzle; The total value of the counters is 486, so halve this to get 243. Now, arrange the counters to equal this amount twice.

The graph on the left (Coronavirus) is for a time period of 30 days, while the one on the right (SARS) is for 8 months! Very poor graphical comparison and hardly relevant, unless it is attempting to downplay the seriousness of the coronavirus?

10 x 9 x 8 + (7 + 6) x 5 x 4 x (3 + 2) x 1 = 2020

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]

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