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Question : 12 of 160
Marks:
+1,
-0
Solution:
Let,
‌‌y=cos−1(‌−x) =cos−1(4(‌)3−3(‌)) Let
‌‌‌=cos‌A then,
A=cos−1‌ Also,
‌‌y=cos−1(4cos3A−3‌cos‌A) =cos−1(cos‌3‌A) =3A=3cos−1(‌) ∴‌‌‌=‌3cos−1(‌) =3×‌×‌(‌) =3×‌×‌=−
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