Ok so guess what...school tomorrow :( but oh well. I have been swamped with basically soccer with the practices and games and the tourny so I barely remember anything and im not ready to go back to school and learn more. But i do remember law of sines so i guess i will talk about that.
Law of sines works for non right triangles and it only works if you have a angle/side pair. The formula for law of sines is sinA/a=sinB/b=sinC/c. Big letters are the angles and little letters are the sides in triangle ABC. If you have angle A, angle B and side a then you will look for the side opposite of angle B. you will cross multiply to where ur problem will look like: bsinA=asinB. Then you divide by sin A and solve completely using ur calculator. Then you found your side b.
For what i need help with is remembering law of cosines so that way that bridge thing will go easier and im looking at my notes and im lost for some reason so i would be thankful if someone helped me.
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Law of Cosines:
ReplyDelete(opp. side) = (adj. side)^2 + (other adj. side)^2 - 2(adj. side)(other adj. side) cos (angle between)
*you use the law of cosines when you can't use law of sines
* in other words, when you have: a non-right triangle, an angle measure with an unknown opposite side, and two side lengths on each side of that angle measure or when you have all three sides and no angle
Example1 (when given an angle & looking for the 3rd side):
you have a triangle ABC, angle C is 32 degrees, a = 5, and b = 6. Find c.
first you plug the values into the formula..
x^2 = 5^2 + 6^2 - 2(5)(6) cos (32 degrees)
x = sqrt of ((6^2 + 5^2 - 2(5)(6) cos 32 degrees))
x = 3.181
i hope this helped...
Law of Cosines:
ReplyDelete(opp. side) = (adj. side)^2 + (other adj. side)^2 - 2(adj. side)(other adj. side) cos (angle between)
you use the law of cosines when you can't use law of sines because you have either a non-right triangle, an angle measure with an unknown opposite side with two side lengths on each side of that angle measure or when you have all three sides and no angle
so law of cosines is the easiest method to use for solving your triangles for the bridge because you'll know the measurements for all of the side lengths because you make them up and you'll use those length measuments plugged into the law of cosine formula to get the angle measurements.