Open book - Same as a dihedral or inside corner. Two panes of rock join in an acute or obtuse corner that faces left or right.
两面角或者内角。两块岩石会聚成锐角或者钝角，向左或者向右。The pilot and copilot each have a set, and there is a pair of shared DUs (display units) in the center (arranged top-and-bottom).
正驾驶和副驾驶面前各有一组，在两人中间（上下呈钝角排列）有一对共用的DU（显示设备）。Look up words and concepts like abacus, Thales' theorem, obtuse triangle and a lot more in this special site.
MathGlossary：这里可以查找像算盘、泰勒斯定理，钝角三角形等等更多的单词以及概念。wing greenish white, usually ca. as long as nutlets, rarely longer, parallel on both sides, wings spreading at obtuse or right angles.
翅带绿色白色，通常与小坚果等长，很少较长，平行的两面，翅张开成钝角或直角。Finally, Please re-sharpen barb area. On this area, no need to re-sharpen to acute angle. Please re-sharpen to obtuse angle.
最后，开始磨倒钩区，这部分不需要锐角角度来磨，保持钝角角度磨就可以了。an cut angle at the roots of adjacent straight teeth is an obtuse angle.
相邻直齿在齿根处的交角为钝角。Only rubber shoes, or running shoes with nails' length less than 6 mm will be allowed in the sports ground.
运动员只能穿著胶鞋或钉长不超过6毫米的钝角钉鞋进场。Leaves broadly oval, basal sinuses rounded, rarely forming an obtuse angle.
叶宽卵圆形，基部的凹缺圆形，很少形成一个钝角。On a vacation at home, Louis, age 15, picked up a blunt awl.
度假在家，路易，15岁，拿起一把钝角锥。