Question

If sinA1, + sinA2 + sinA3 = 3 then cosA1+ cosA2 + cosA3 =
(A) 3
(B) 2
(C) 1
(D) 0​

Answer 1

Answer:(D) 0

Step-by-step explanation:

Sina1 + sina2 + sina3 = 3

we know ,

sine maximum value= 1

so, above expression is correct only when , sina1 = sina2 = sina3 = 1

e.g a1 = a2 = a3 = 90°

but we know ,

cos90° = 0

so, cosa1 = cosa2 = cosa3 = 0

hence,

cos a1+cos a2+cos a3=0

Answer 2

Answer:

Since the maximum value of SinA is 1

So

sinA1 + sinA2 + sinA3 = 3 holds only when

sinA1 = sinA2 = sinA3 = 1

So

A1 =A2 = A3 = 90°

SO

cosA1+ cosA2 + cosA3

= cos90° + cos90° + cos90°

= 0+0+0

= 0

So the required answer is D) 0