Q. 18 A5.0( 2 Votes )

If , then find the values of cos θ and sin θ.

Answer :


We know that,



Or



Let,


Side adjacent to angle θ =AB = 21k


The side opposite to angle θ =BC = 20k


where k is any positive integer


Firstly we have to find the value of AC.


So, we can find the value of AC with the help of Pythagoras theorem


(AB)2 + (BC)2 = (AC)2


(21k)2 + (20k)2 = (AC)2


(AC)2 = 441 k2 +400 k2


(AC)2 = 841 k2


AC =√841 k2


AC =±29k


But side AC can’t be negative. So, AC = 29k


Now, we will find the sin θ



Side opposite to angle θ = BC = 20k


and Hypotenuse = AC = 29k


So,


Now, we know that,



Side adjacent to angle θ = AB =21k


Hypotenuse = AC =29k


So,


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