SOLUTION: In (triangle)ABC, if A and B are acute angles, and sin A =10/13 , what is the value of cos A ? please help, need to know how to do this on my calculator too. thank you

Question 30116: In (triangle)ABC, if A and B are acute angles, and sin A =10/13 ,
what is the value of cos A ?
please help, need to know how to do this on my calculator too.
thank you
Answer by Paul(988) (Show Source): You can put this solution on YOUR website!
In triangle AB, A and B are acute angles so. AC and BC are right angles.
Sin A = 10/13
13 is the hypotenuse side and 10 is the opposite side.
To find cos A.
From pythagorean thereom:

b=8.3

SO the value for cos A is 8.3/13
cos A=0.63 take the inverse sine of cosine:
cos A=51 degrees.
PAul.
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