So, when you go to polar coordinates, basically all you have to remember on the side of integrate is that x becomes r cosine theta. y becomes r sine theta.

在极坐标系里，要记住在积分一侧,只是把x变成rcosθ，y变成rsinθ

youdao

So anyway, this is the origin, and then the last side, y equals zero, x So, somehow, in the change of variables, this square becomes this triangle.

变成另一个点，无论如何，这就是原点，最后一条边，y=0，一直变化，最终变成了v=0，and，x，varies，just，becomes，v，equals，zero。,所以，在变量替换的过程中，这个正方形变成了三角形。

youdao

The industrial city and tourist center of Niagara Falls, N. Y. , is adjacent to the American side of the falls.

毗邻瀑布美国边境的是纽约州尼亚加拉瀑布的工业城市和旅游中心。

youdao

The Parc y Scarlets side remain the bottom-placed Welsh region, the Blues and Dragons in their sights as they seek qualification for next season's Heineken Cup.

BBC: Scarlets 25-8 Ulster

Allon is the president and CEO of Manhattan Media, which publishes titles ranging from local newspapers Our Town and the West Side Sprit to the glossy Avenue magazine and the insider-y Hamptons chronicle Dan's Papers.

WSJ: Republican Tom Allon drops out of NYC mayor's race

Estonia, ranked 113 in the Fifa world rankings, offered little to worry the Wales defence as the home side looked comfortable in possession on a perfect surface at Parc y Scarlets.

BBC: Wales 1-0 Estonia