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# Help. ​

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Help.

NotSoSmart  Mar 28, 2017
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#1
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BA=16 ft because if one angle is 90 and another one is 45, the triangle is equilateral, so the third angle is 45.

Pythagorean theorem: BC²=AB²+AC²
BC²=256+256
BC²=512

BC=√512=16√2 ft.
Why 16√2? To put "16" under √ you need 16*16=256. Then you need 16*2=√512. So √512=16√2.

vikkiry  Mar 28, 2017
#2
+79911
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1. We can sovle the first one using the Law of Cosines.......we need to find the angle opposite  the greatest side

42^2   =  34^2 + 28^2  - 2 (34)(28)cos (theta)

cos (theta)   = [ 42^2 - 34^2 - 28^2]   / [ -2 * 34 * 28 ]

arccos  ( [ 42^2 - 34^2 - 28^2]   / [ -2 * 34 * 28 ] )   = theta  ≈ 84.7°

Since the greatest angle lies opposite the greatest side, this triangle is acute

2. Since angle B = 45, then so does angle C.......and if two angles of a triangle are equal, then the sides opposite those angles are also equal......so  CA  = BA

CPhill  Mar 28, 2017

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