Trigonometrical Equations 1 Question 17

17. The general solution of the trigonometric equation sinx+cosx=1 is given by

(1981, 2M)

(a) x=2nπ;n=0,±1,±2,

(b) x=2nπ+π/2;n=0,±1,±2,

(c) x=nπ+(1)nπ4π4;n=0,±1,±2,

(d) None of the above

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Answer:

Correct Answer: 17. (c)

Solution:

  1. Given, sinx+cosx=1

On dividing and multiplying each terms by 2, we get

12sinx+12cosx=12sinxcosπ4=cosxsinπ4=12sinx+π4=sinπ4x+π4=nπ+(1)nπ4x=nπ+(1)nπ4π4,nI



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