InterviewSolution
Saved Bookmarks
| 1. |
If `(sin^(4)theta)/(a)+(cos^(4)theta)/(b)=(1)/(a+b),` then which one ofhte following is incorrect?A. `(sin^(4)theta)/(a^(2))=(cos^(4)theta)/(b^(2))`B. `(sin^(4)theta)/(b^(2))=(cos^(4)theta)/(a^(2))`C. `(sin^(8)theta)/(a^(3))+(cos^(8)theta)/(b^(3))=(1)/((a+b)^(3))`D. `sin^(4)theta=(a^(2))/((a+b)^(2))` |
|
Answer» Correct Answer - B We have, `(sin^(4)theta)/(a)+(cos^(4)theta)/(b)=(1)/(a+b)` `(a+b)((sin^(4)theta)/(a)+(cos^(4)theta)/(b))=(sin^(2)theta+cos^(2)theta)^(2)` `impliessin^(4)theta+cos^(4)theta+b/asin^(4)theta+a/bcos^(4)theta` `" "=(sin^(4)theta+cos^(4)theta+2sin^(2)thetacos^(2)theta)` `(sqrt((b)/(a))sin^(2)theta-sqrt((a)/(b))cos^(2)theta)^(2)=0` `impliessqrt((b)/(a))sin^(2)theta=sqrt((a)/(b))cos^(2)theta` `impliesbsin^(2)theta=acos^(2)theta` `implies(sin^(2)theta)/(a)=(cos^(2)theta)/(b)=(sin^(2)theta+cos^(2)theta)/(a+b)` `impliessin^(2)theta=(a)/(a+b)and cos^(2)theta=(alpha)/(a+b)` Clearly, these values satisfy options (a), (c ) and (d) only. Hence, option (b) is incorrect. |
|