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I wonder if anyone can help with this question. It's a part of a Differential Geometry exam question which I can't get!
A map [itex]\mathbb{R}^3 \times \mathbb{R} \rightarrow \mathbb{R}^3 [/itex] is defined by
[tex] ((x,y,z),t) \longmapsto \left( \frac{x}{z\sinh t+\cosh t},\frac{y}{z\sinh t+\cosh t},\frac{z\cosh t+\sinh t}{z\sinh t+\cosh t}\right) [/tex]
Show that this determines a mapping [itex] f:S^2\times \mathbb{R} \rightarrow S^2 [/itex].
I tried substituiting polar coordinates for S2 in place of (x,y,z) in the above function. Then I figured that if the function's image is a subset of S2, then the coordinates must satisfy [itex]z=\sqrt{1-x^2-y^2}[/itex]. However, I can't get this to work, and so it's probably not the correct method!
Any help/hints would be greatly appreciated!
A map [itex]\mathbb{R}^3 \times \mathbb{R} \rightarrow \mathbb{R}^3 [/itex] is defined by
[tex] ((x,y,z),t) \longmapsto \left( \frac{x}{z\sinh t+\cosh t},\frac{y}{z\sinh t+\cosh t},\frac{z\cosh t+\sinh t}{z\sinh t+\cosh t}\right) [/tex]
Show that this determines a mapping [itex] f:S^2\times \mathbb{R} \rightarrow S^2 [/itex].
I tried substituiting polar coordinates for S2 in place of (x,y,z) in the above function. Then I figured that if the function's image is a subset of S2, then the coordinates must satisfy [itex]z=\sqrt{1-x^2-y^2}[/itex]. However, I can't get this to work, and so it's probably not the correct method!
Any help/hints would be greatly appreciated!