Question

If 2sinx+3siny=5 then find cosx+3cosy=?

Answer 1

answer : 0

explanation : this is conceptual question. let's think about maximum value of sinx and siny

you know as well, maximum value of sine function is 1 {because -1 ≤ sine ≤ 1 }

so, maximum value of sinx = 1

and also maximum value of siny = 1

now, 2sinx + 3siny = 2 × 1 + 3 × 1 = 5 (RHS)

it means, 2sinx + 3siny = 5 only when sinx = 1 and siny = 1

or, x = π/2 and y = π/2

now, cosx + 3cosy

= cos(π/2) + 3cos(π/2)

= 0 + 3 × 0 = 0

hence, value of cosx + 3cosx = 0

Answer 2

Answer:

Step-by-step explanation:

from apti point of view ,here we se a short cut trick

i.e.  for 2sinx + 3 siny=5 i.e. 2+3=5

     &   cosx + 3cosy = 4 (i.e. 1+3 = 4) so answer is 4