1.

If cosC + cosD = x, then value of x is1). $2cos\frac{[(C+D)]}{2}sin\frac{[(C-D)]}{2}$2). $2sin\frac{[(C+D)]}{2}sin\frac{[(C-D)]}{2}$3). $2cos\frac{[(C+D)]}{2}sin\frac{[(C-D)]}{2}$4). $2sin\frac{[(C+D)]}{2}cos\frac{[(C-D)]}{2}$

Answer»

Its TOUGH but OPTION 1 SEEMS CORRECT



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