This is how it's said in agriculture, geography, the landscape and construction industries, and skiing.
(I've been studying terrain management.)

180,000 refs - examples:

The catchment area of the River Chagres covers 326 225 ha. the greater part of which is on slopes of more than 45 0. Forests covered 83% of the area in 1952 ...
www.fao.org/DOCREP/006/AD077E/AD077e17.htm

Steep slopes of more than 45°. The most important gravitational mass movement occurred on 30 April 1974 in Maranguape City (Fig. 12a) ...
www.springerlink.com/index/LYWDJXDXC4DKQV15.pdf

About 1000 tons of steel must be installed on slopes of more than 45 degrees, and it is only possible to transport loads via helicopter or a renovated ...
www.hydroworld.com



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Note added at 1 hr (2010-02-20 21:52:47 GMT)
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180,000 hits for "slopes of more than 45"
1,080 hits for "slopes above 45" - and not from professional journals

Stabilization system for soil slopes - Patent 6524027
by M Fabius - 2003 - Related articles
On steep slopes having generally less than 45 degrees of inclination to the ... mesh or fibrous material placed over or near the soil surface before or ...
www.freepatentsonline.com/6524027.html

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Note added at 1 hr (2010-02-20 22:12:43 GMT)
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Stabilization system for soil slopes - Patent 6524027
by M Fabius - 2003 - Related articles
A method of stabilizing slopes of a soil embankment is provided using a stabilization system for slopes having generally less than 45 degrees of inclination ...
www.freepatentsonline.com/6524027.html

Hillsides with slopes above 45 degrees

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Note added at 28 mins (2010-02-20 21:07:00 GMT)
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... in regions above 1800 meters of altitude (8.42 ha), the third upper part the hills (18.67 ha); an hillsides with slopes above 45 degrees (92.96 ha); ...

www.scielo.br/scielo.php?pid=S0100...script=sci...

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Note added at 29 mins (2010-02-20 21:07:40 GMT)
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... third of hills (49,7 ha); hillsides with slopes above 45 degrees (27,5 ha); ... encostas com declividade superior a 45 graus (27,5 ha); nascentes e suas

www.bioline.org.br/abstract?cf05020

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Note added at 30 mins (2010-02-20 21:08:38 GMT)
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OR HILLS WITH SLOPES....

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Note added at 31 mins (2010-02-20 21:09:19 GMT)
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Determine the degree of your slope for your hillside. It's easiest to plant hills with a 45 degree slope or less. Hills with slopes between 45 degrees and ...

www.ehow.com › ... › Soil

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Note added at 31 mins (2010-02-20 21:09:45 GMT)
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http://www.ehow.com/how_5161508_plant-erosion-control.html

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Note added at 45 mins (2010-02-20 21:24:14 GMT)
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ESQUECI DE TRADUZIR AS PALAVRAS EM PARÊNTESES:

>>>>>>>>>> (100 percent slope)




A slope of 45 degrees equals 100 percent slope. As slope angle approaches vertical (90 degrees), the percent slope approaches infinity. ...

http://support.esri.com/index.cfm?fa=knowledgebase.gisDictio...



A slope of 45 degrees is a slope of 100 percent because at this angle, the difference in elevation between two points 100 meters apart horizontally is 100 ...

www.pasitesearch.com/.../help.../E_Soil_Slope.htm

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Note added at 47 mins (2010-02-20 21:25:33 GMT)
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PERDÃO, QUIS DIZER "ENTRE PARÊNTESES" :)

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Note added at 2 hrs (2010-02-20 23:25:42 GMT)
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OR YOU CAN SAY>>>>> "OVER 45 DEGREES"

Sugestão. Espero que ajude! :)



Determine the degree of your slope for your hillside. It's easiest to plant hills with a 45 degree slope or less. Hills with slopes between 45 degrees and ...

http://www.ehow.com/how_5161508_plant-erosion-control.html



31 Oct 2006 ... A slope of 45 degrees equals 100 percent slope. As slope angle approaches vertical (90 degrees), the percent slope approaches infinity. ...

http://support.esri.com/index.cfm?fa=knowledgebase.gisDictio...



In skiing, any slope over 45 degrees (or 100 percent) is pretty dang steep. http://www.greenbeltconsulting.com/a...tionships.html ...

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Note added at 3 hrs (2010-02-20 23:49:00 GMT)
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HILLSIDES = ENCOSTAS

SLOPES= DECLIVE

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Note added at 3 hrs (2010-02-21 00:32:10 GMT)
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Hillsides with slopes over 45 degrees (100 percent slope)

this is how I would translate this