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1/9 sin^4 x + 1/16 cos^4 x = 1/25

Source: Flanders Math Olympiad 2020 p1

December 24, 2022

trigonometry

Problem Statement

Let

x

be an angle between

0^o

and

90^o

so that

\frac{\sin^4 x}{9}+\frac{\cos^4 x}{16 }=\frac{1}{25} .

Then what is

\tan x