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Solve the triangle. Round lengths to the nearest tenth and angle measures to the nearest degree. a = 7, b = 7, c = 5
 8 months ago
 8 months ago
Solve the triangle. Round lengths to the nearest tenth and angle measures to the nearest degree. a = 7, b = 7, c = 5
 8 months ago
 8 months ago

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britbrat4290Best ResponseYou've already chosen the best response.0
B. A = 69°, B = 69°, C = 42°??
 8 months ago

mebsBest ResponseYou've already chosen the best response.0
\[7^{2} = 7^{2} + 5^{2}  2(7)(5)cosA\]
 8 months ago

britbrat4290Best ResponseYou've already chosen the best response.0
my answers need to be in degrees
 8 months ago

mebsBest ResponseYou've already chosen the best response.0
you get \[cosA = \frac{ 25 }{ 70 }\] than do arc cosine. you get angle 69.07
 8 months ago

britbrat4290Best ResponseYou've already chosen the best response.0
i need degrees for a b n c ??
 8 months ago

mebsBest ResponseYou've already chosen the best response.0
you get angles 41.8 and 69.07. again
 8 months ago

britbrat4290Best ResponseYou've already chosen the best response.0
A. A = 70°, B = 70°, C = 40° B. A = 69°, B = 69°, C = 42° C. A = 42°, B = 69°, C = 69° D. A = 69°, B = 42°, C = 69°
 8 months ago

genius12Best ResponseYou've already chosen the best response.0
Note that the triangle is isosceles:dw:1375984026354:dw
 8 months ago

britbrat4290Best ResponseYou've already chosen the best response.0
ok ? still confused
 8 months ago

genius12Best ResponseYou've already chosen the best response.0
Now use the cosine law:\[\bf a^2=b^2+c^22bc \cos(A) \implies 5^2=7^2+7^22(7)(7)\cos(A)\]Note that 'A' is the angle opposite side BC. Now rearrange and solve for cos(A):\[\bf \implies \cos(A)=\frac{73}{98}=0.7445 \implies \cos^{1}(0.7445)=A=41.884 \ degrees\]
 8 months ago

genius12Best ResponseYou've already chosen the best response.0
Now because the triangle is isosceles, the remaining two angles B and C are equal so we can find each of them by subtracting A from 180 and dividing the result by 2:\[\bf \angle B=\angle C=\frac{ 180 41.884}{ 2 }=69.058 degrees\]Rounding off our results to the nearest degree we get:\[\bf \angle A =42 \ degrees\]\[\bf \angle B=\angle C=69 \ degrees\] @britbrat4290
 8 months ago

genius12Best ResponseYou've already chosen the best response.0
@britbrat4290 So your answer is correct =]
 8 months ago
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