Q18 of 27 Page 301

Using the formula,, find the value of cos 30°, it being given that cos 60° = 1/2 .

Given: cos A = , …………………….(1)


cos 60° = 1/2


To find: cos 30°


By putting A = 30° in equation (1), we get the following:


cos 30° =


=


= = √3/2


∴ cos 30° = √3/2


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