Question 1135553
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           This problem is to solve it in  5  (five,  FIVE)  lines.



<pre>
For <U>any</U> triangle, its area is half the product of the lengths of any its two sides and the sine of the angle between them.


In your case, the Area = {{{(1/2)*b*c*sin(A)}}}.


Substituting your data, you have {{{(15*sqrt(7))/4}}} = {{{(1/2)*5*4*sin(A)}}}.


From here,  sin(A) = {{{(2*15*sqrt(7))/(4*5*4)}}} = 0.992167.


Then  for angle A you have TWO possible values  m ( < A ) = 82.82°  and  m ( < A) = 180° - 82.82° = 97.08°.    <U>ANSWER</U> 
</pre>

Solved.