Ta có:

`tan \beta . cot \beta =1`

`=> cot \beta = 1: tan \beta`

`=> cot \beta = 1: 2\sqrt(2) =(\sqrt(2))/4`

Ta có:

`1 + tan^2 \beta = 1/(cos^2 \beta)`

`=> cos^2 \beta . ( 1+ tan^2 \beta) = 1`

`<=>cos ^2 \beta = 1/(tan^2 beta +1)`

`<=> cos^2 \beta = 1/((2\sqrt(2)^2+1)`

`<=> cos^2 \beta = 1/9`

`<=> cos \beta= +-1/3 ~~ +- 0,33`

Ta có:

`1 + cot^2 \beta =1/(sin^2\beta)`

`<=> sin^2 \beta . (1 + cot^2 \beta ) =1`

`<=> sin^2 \beta = 1/(1 + cot^2 \beta)`

`<=> sin^2 \beta = 1/(1 + ((\sqrt(2)/(4))^2 )`

`<=> sin^2 beta = 8/9`

`<=> sin \beta = +- (2\sqrt(2))/3 ~~ +- 0,94`.