Something I’ve Learned in Math This Week

This week in Math, I learned how to find the measure of an angle of a right triangle with two side lengths. First you need to need to label the triangle sides relative to the angle you are trying to find. The hypotenuse is the longest side. The adjacent is the side next to the angle that isn’t the hypotenuse. The opposite is the side opposite of the angle. Next, with the two side lengths you are given, you need to find the trigonometric function that works with the side lengths you are given. sin=opposite/hypotenuse, cos=adjacent/hypotenuse, and tan=opposite/adjacent.

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As you can see in this example, we are given the side lengths of opposite and adjacent, therefore, we use tan=opposite/adjacent. We know that in this example, opposite=9.7 and adjacent=5.2. So in our calculator we would type in \tan^{-1}(\frac{9.7}{5.2}) then press “=”. The answer we get should be something like 61.80502… which would round to 62, so our answer would be x=62^\circ, and that is how you find the measure of an angle of a right triangle with only two side lengths.

Something I’ve Learned in Math This Week

This week in Math, I learned how to calculate the surface area of a sphere. All you have to do is insert the measurements into this formula: 4πr^2 and you will find your answer. In this formula, you will need either the radius or the diameter which you can then turn to radius.

sphere

The radius is the distance between the centre of the circle to the outer edge and is represented by “r” in the diagram above. If you are given the diameter, represented by “d” above, all you need to do is divide that number by 2 and take that number.

Let’s say for example that the radius(r) of the circle above was 2. All you would need to do is plug that number into the formula(4πr^2) to figure out your answer like this on your calculator:

SA = 4πr^2 = 4·π·2^2 ≈ 50.26548
This can be used when measuring out wrapping paper for a spherical gift. If you plan to give someone a ball this Christmas, you can use this formula to calculate the surface area of that ball so you don’t waste any wrapping paper.

Something I Have Learned in Math This Week(Oct 7)

This week I learned how to read measurements on a micrometer.

First you have to put your object into your micrometer then twist the thimble it until the object is tight inside. Then, you would read the last visible number on the sleeve/barrel which will tell you how many millimeters to start with by 0.5mm increments. Then, you would look at the number on the thimble that matches up with the centre line and divide that number by a hundred then add that to your initial measurement on the barrel.

measuring_metric_micrometer

In this example, you can see that the last visible number on the barrel is 16.5. You can also see that the number on the thimble reads 16. With that you add 0.16 to 16.5 which equals 16.66, so the measurement of your object is 16.66mm.

GCF/LCM

Finding GCF(ladder method):

1. Take your numbers(108 & 144) and line them up with an upside down division symbol

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2. Find a number that both your numbers are divisible by(4), then divide both your numbers by the common factor.

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3. Continue dividing your resulting numbers by common factors until all your numbers only have a common factor of 1.

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4. Multiply the numbers on the left to get your GCF: GCF = 4 x 9 = 36

5. Now you got your GCF!

Finding LCM(ladder method):

1. Take your numbers(108 & 144) and line them up with an upside down division symbol

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2. Find a number that both your numbers are divisible by(4), then divide both your numbers by the common factor.

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3. Continue dividing your resulting numbers by common factors until all your numbers only have a common factor of 1.

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4. Multiply all your outer numbers together to get your GCF: GCF = 4 x 9 x 3 x 4 = 432

5. Now you got your LCM!

Conclusion: I like the method I found better because you don’t need to do prime factorization. I also like it better because you don’t need to put your face against the paper looking for repeated prime factors. The method I found is also less writing because it doesn’t use prime factorization and just factorization.