15.已知角α的终边经过点 P(5,-12) ,求sinα,cosα和tanα的值.
4.已知 sin alpha =-dfrac (3)(5), 且α是第三象限的角,则 cos alpha = __ ,-|||-tan alpha = __ o
已知 cos (dfrac (pi )(4)+x)=dfrac (3)(5), 求sin2x的值.
已知角θ的终边经过点P((sqrt(2),-sqrt(7))),则cos((θ+(π)/(3)))=( )A. $\frac{{\sqrt{6}+\sqrt{
例1(1)(2021·全国甲卷)若 alpha in (0,dfrac (pi )(2)), tan2α-|||-=dfrac (cos alpha )(2-s
4.在 Delta ABC 中, cos C=dfrac (2)(3) =4 ,BC=3, 则 tan B= ()-|||-
lim _(xarrow 0)dfrac (tan 5x)(3x)=dfrac (5)(3) ()
1.已知 为两个随机事件,且 (A)=dfrac (1)(2) , (B)=dfrac (3)(5) , (B|A)=dfrac (4)(5), 求:-|||-
(5)设 (A)=dfrac (1)(3), (B)=dfrac (1)(4), (Acup B)=dfrac (1)(2), 则 (overline (A)c
dfrac (1)(2)x+dfrac (1)(3)=dfrac (1)(4)x-dfrac (1)(5)