if A+B+C=180 then find the value of secA(cosBcosC-sinBsinC)

Asked by  | 1st Sep, 2012, 12:04: PM

Expert Answer:

A + B + C = 180°.

Now, sec A (cos B.cos C - sin B.sin C)

= sec A.cos (B + C)

= sec A. cos (180° - A)

= sec A. (-cos A)

= -1

Answered by  | 2nd Sep, 2012, 12:14: PM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.