已知sinθ+cosθ=23,则cos2θ+5π2的值为( )_刷题宝

题干

已知sinθ+cosθ=

2

3

,则cos2θ+π

5

2

的值为( )

A： $\frac{7}{9}$

B： $- \frac{7}{9}$

C： $- \frac{4 \sqrt{2}}{9}$

D： $\frac{4 \sqrt{2}}{9}$

上一题下一题 0.0难度选择题更新时间:2019-06-05 11:12:45

答案(点此获取答案解析）

A

同类题1

吸毒者由于经常共用不洁注射器注射毒品，很容易感染____病．

同类题2

下列各组词语中，汉字书写全都正确的一组是（）

同类题3

如图所示小球沿水平面通过O点进入半径为R的半圆弧轨道后恰能通过最高点P，然后落回水平面．不计一切阻力．下列说法正确的是

①．小球落地点离O点的水平距离为2R．
②．小球落地点时的动能为5mgR/2．
③．小球运动到半圆弧最高点P时向心力恰好为零．
④．若将半圆弧轨道上部的1/4圆弧截去，其他条件不变，则小球能达到的最大高度比P点高0.5R．

同类题4

I have a good friend at home. Her name is Mimi. She is white and yellow. She is very cute. I play with her when(当……的时候) I have time. She likes fish very much. When she is behind (在……之后) the sofa or in her box, you can’t see her. When I sit on the sofa, she sits with me. In the evening I do my homework at my desk, and she is on the desk. At that time I put her down(放下). Then she sits next to me. Is she a good friend of mine?

同类题5

若关于x的一元二次方程（a﹣1）x²﹣x+1=0有实数根，则a的取值范围为____．

小学学科试题库

初中学科试题库

高中学科试题库