4.已知∠A,∠B,∠C均为锐角,若tanA>$\sqrt{3}$,sinB<$\frac{1}{2}$,cosC=$\frac{\sqrt{2}}{2}$,则( )
| A. | ∠A>∠B>∠C | B. | ∠C>∠B>∠A | C. | ∠B>∠C>∠A | D. | ∠A>∠C>∠B |
3.在Rt△ABC中,∠C=90°,BC=a,AC=b,且3a=4b,则∠A的度数为( )
| A. | 53.48° | B. | 53.13° | C. | 53.13′ | D. | 53.48′ |
2.△ABC中,tanA=1,cosB=$\frac{\sqrt{3}}{2}$,则△ABC为( )
| A. | 锐角三角形 | B. | 钝角三角形 | C. | 直角三角形 | D. | 不能确定 |
19.在△ABC中,∠C=90°,a=5,c=13,用计算器求∠A约等于( )
0 308544 308552 308558 308562 308568 308570 308574 308580 308582 308588 308594 308598 308600 308604 308610 308612 308618 308622 308624 308628 308630 308634 308636 308638 308639 308640 308642 308643 308644 308646 308648 308652 308654 308658 308660 308664 308670 308672 308678 308682 308684 308688 308694 308700 308702 308708 308712 308714 308720 308724 308730 308738 366461
| A. | 14°38′ | B. | 65°22′ | C. | 67°23′ | D. | 22°37′ |