Solving $\mathrm{cos}3x=\frac{1}{\sqrt{2}}$

nidantasnu
2022-07-03
Answered

Solving $\mathrm{cos}3x=\frac{1}{\sqrt{2}}$

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Dual of the formula for Euclidean triangles

It’s well known that the trigonometric area formula for Euclidean triangles is

$S=\frac{1}{2}ab\mathrm{sin}C$ (1.1)

Is there a such formula for hyperbolic triangles?

Is there a proof for (1.1) by using law of cosines?

It’s well known that the trigonometric area formula for Euclidean triangles is

Is there a such formula for hyperbolic triangles?

Is there a proof for (1.1) by using law of cosines?