Let ABCD be a square, and let M and N be the midpoints of BC and CD, respectively. The value of \sin \angle MAN can be expressed in the form m/n, where m and n are relatively prime positive integers. Find m + n.

Respuesta :

Answer:

s[tex]\sqrt{5}[/tex]

Step-by-step explanation:

Hi there! I've graphed a square, with its midpoints so that you can visualize it better (below).

1) Starting with a square ABCD, a square since it has four equal angles, its sides (s) they have the same size.

2) The first statement says the sin M∠AN can be expressed in terms of [tex]\frac{m}{n}[/tex] and m, and n are relatively prime positive integers, in other words, there is only one divisor of m and n: 1. And n can never be zero.

With that in mind, let's start calculating:

Sin MAN=

[tex]sin A =\frac{m}{n} \\ m=?\\[/tex]

m=?

Well, m is the hypotenuse of Δ AND

Then, [tex]m^{2} =s^{2}+(\frac{s}{2})^2\\ m=\sqrt{s^{2}+\frac{s^{2}}{4}} \\ m=\sqrt{\frac{5s^{2}}{4}} \\ m=\frac{s\sqrt{5}}{2}[/tex]

n=?

Well, n is also a hypotenuse. But the Δ ABM one.

Then, similarly to m

n²=(s)²+(s²/2)²

n²=s²+s²/4

n²=5s²/4

n=[tex]\frac{s\sqrt{5}}{2}[/tex]

3) Finally, we're now able to find the sum m +n

m + n = ?

[tex]m =(\frac{s\sqrt{5}}{2} )+ n =(\frac{s\sqrt{5}}{2}) =\frac{2s\sqrt{5}}{2} =s\sqrt{5}[/tex]

And review and test our work.

In the first part of the question, it was said the value of the sin of MAN, i.e. the sin of ∠A = [tex]\frac{m}{n}[/tex]. The distance between a midpoint and a vertex is the same. So, MA = NA

You can choose a number, let's say a square whose sides measure 4 units and do the test.

So MA = m and n=NA and sin ∠A is 90º

sin ∠A = MA/NA

sin 90º =MA/NA

1=1 correct

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