Q. 12 B4.2( 5 Votes )

Let us write whether the following statements are true of false:

(i) The value of cos54° and sin36° are equal.

(ii) The simplified value of (sin 12° - cos78°) is 1.

Answer :

(i) The statement is true


cos54° = cos(90 - 36)°


= sin36°


[cos(90 - θ) = sinθ]


the value of cos54° and sin36° has same values


(ii) The given statement is False


sin12° - cos78°


sin12° - cos(90 - 12)°


sin12° - sin12°


= 0


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