if sinA.secA = -1 and a lies in 2nd quadrant find sinA and secA.

Asked by swati gaur | 31st May, 2013, 12:54: PM

Expert Answer:

sinA.secA = -1
sinA/cosA = -1
sinA = -cosA
 
Now, A lies in second quadrant, hence sinA >0 but, cosA <0  which is also proved through the above equation
Also, |sinA| = |cosA| can be true only if A = pi/4
 
Hence, the solution of this equation would be A = pi/2 + pi/4 (since A is in second quadrant) 
A = 3pi/4

Answered by  | 31st May, 2013, 07:37: PM

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