purnimat
purnimat purnimat
  • 06-08-2020
  • Mathematics
contestada

If 3sinA+4cosA=5 then find the value of cosA

Respuesta :

Rushal
Rushal Rushal
  • 06-08-2020

Answer:

Cos A =1.4

Step-by-step explanation:

3sinA=5-4cosA; square both sides: 9sin^2(A)=25-40cosA+16cos^2(A);

9-9cos^2(A)=25-40cosA+16cos^2(A); 25cos^2(A)-40cosA+16=0=(5cosA-4)^2.

cosA=4/5 so sinA=3/5 (√(1-16/25) and sinA+cosA=7/5=1.4.

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