Question

In this triangle, which of the following is true?​

Answer 1

We know that this is a right triangle, so one of the sides has to be 90 (indicated by the square on the corner)  The angles of all triangles must add to exactly 180.  Subtract 90 and 35 from 180

If we do that, we get 55.  We know that the unknown angle is 55 now.  Now, it asks us for b.  We can pythagoras theorem which states that (a^2 + b^2 = c^2)  We already know c (c is 20)  It does not tell us 2 of the sides but we do know that the answer is either B or D.  

The side opposite of 90* should be the largest.  The size opposite of 55 would be the second largest one.  The side opposite of 35 would be the smallest one.  Using pythagoras theorem again, I can try plugging in both 11.47 and 16.38 with c^2 - b^2 = a^2  

11.47:

400 - 132 =268  (sq root now = 16.37) this would mean that A is larger than B.  B should be larger than A.  Try the other one

16.37:

400 -268 = 132 (sq root = 16.37) this would mean that B is larger than A which is what we want.

Thus, 16.37  = B and the last option would be correct (D)

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