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anonymous
 5 years ago
right triangle has angle A and B. Cos B=3/4
the hypotenuse is 5. find x (opposite) and y (adjacent) the B is above the 90 degrees, and A is next to it (sorry hard to explain cause there's a drawing)
anonymous
 5 years ago
right triangle has angle A and B. Cos B=3/4 the hypotenuse is 5. find x (opposite) and y (adjacent) the B is above the 90 degrees, and A is next to it (sorry hard to explain cause there's a drawing)

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dumbcow
 5 years ago
Best ResponseYou've already chosen the best response.0cosB = adj/hyp = y/5 cosB = 3/4 > y/5 = 3/4 y=(3*5)/4 = 15/4 use pythagorean theorem to find x 5^2 = (15/4)^2 + x^2 x^2 = 25 (225/16) x^2 = (400  225)/16 x = 5*sqrt(7)/4

Yuki
 5 years ago
Best ResponseYou've already chosen the best response.0if the hypotenuse is 5, then cos(B) = opposite / hypotenuse = opp / 5 so 3/4 = opp / 5 by multiplying 5 on both sides, opp = 15/4

dumbcow
 5 years ago
Best ResponseYou've already chosen the best response.0haha i almost made same mistake when i saw 3/4 :)

Yuki
 5 years ago
Best ResponseYou've already chosen the best response.0now if you want to find the adj, you use sin(B) or just use the pythagorean thm. \[5^2 = (15/4)^2 + adj^2\] or sin(B) = sqrt(7) so sin(B) = opposite / hypotenuse = opp / 5 = sqrt(7) so opp =\[5\sqrt{7}\]

Yuki
 5 years ago
Best ResponseYou've already chosen the best response.0I'm making so much mistakes today... sorry for cos(B) it is actually adj / hyp so the adjacent side is 15/4

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0haha. yeah. it's okay, dumbcow explained it. now what if i wanted to find sin(B) would it be (5*sqrt7/4)/5 ?

Yuki
 5 years ago
Best ResponseYou've already chosen the best response.0sin(b) =\[\sqrt{1\cos^2(B)}\] so it is \[\sqrt{7/4}\]
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