Question

Can anyone help me with a few geometry questions?

Answer 1

Several people can, post a question.

Answer 2

My problem wants me to find BC

Answer 3

But please dont just give me the answer... I have more questions like this and I want to truely understand it

Answer 4

Do you know what the sin of 30 degrees is?

Answer 5

If you know about sines, you can set up a relationship between CB and AB. Can you do that?

Answer 6

@Lalalorenzo ?

Answer 7

Can you explain sines to me; I don't know the sine of 30

Answer 8

I'll give you some hints. The sine is the ratio of the length of the opposite side from an angle to the hypotenuse. Here, we can set the

sine of 30 degrees = BC/AB

AB is known and we can get the sin 30

Answer 9

We can re-write this as

BC = (AB)(sin 30)

you can get sin 30 from a calculator, but that particular sin will eventually be memorized as it is a common angle in these types of problems The sin 30 = 1/2

Answer 10

so is the sine of thirty BC/10sqrt6

Answer 11

yes, but you can use my re-written equation since you are trying to find BC

Answer 12

So, now that you know sin 30 and you have the length of AB, you will be able to get the length of BC

Answer 13

You are probably also going to be asked for the length of CD. You now have the length of BC, and CD will be the same length because angle CBD is 45 degrees, just like angle CDB so you have an isosceles triangle in BCD.

Answer 14

You also might be asked the length of BD and/or AC which can be gotten from other trigonometric relationships or easier by the Pythagorean theorem at this point, now that you know BC and CD.

Answer 15

@Lalalorenzo ?