SOLUTION: (1)if sinA=7/25, cos=3/5 where A and B are acute, find without using tables: a)the value of sin (A-B) b) the value of cos(A+B) (2) Find the centre and radius of the circle 4X2

Algebra ->  Trigonometry-basics -> SOLUTION: (1)if sinA=7/25, cos=3/5 where A and B are acute, find without using tables: a)the value of sin (A-B) b) the value of cos(A+B) (2) Find the centre and radius of the circle 4X2      Log On


   



Question 697013: (1)if sinA=7/25, cos=3/5 where A and B are acute, find without using tables:
a)the value of sin (A-B)
b) the value of cos(A+B)
(2) Find the centre and radius of the circle 4X2+4y2-12x+5=0
Please help me out
Thanks

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
(1)if sinA=7/25, cos=3/5 where A and B are acute, find without using tables:
I assume you mean cos(B) = 3/5
cos(A) = 24/25
sin(B) = 4/5
--------------
a)the value of sin (A-B)
= sin(A)cos(B) - sin(B)cos(A)
= (7/25)*(3/5) - (4/5)*(24/25)
= -3/5
---------------
b) the value of cos(A+B)
= coscos + sinsin
= (24/25)*(3/5) + (7/25)*(4/5)
= 4/5
---------------
(2) Find the centre and radius of the circle 4X2+4y2-12x+5=0
Complete the squares
4x%5E2+-+12x+%2B+4y%5E2+=+-5
x%5E2+-+3x+%2B+y%5E2+=+-5%2F4
x%5E2+-+3x+%2B+9%2F4+%2B+y%5E2+=+1
%28x+-+3%2F2%29%5E2+%2B+y%5E2+=+1
Center at (3/2,0)
radius = 1