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如图,在梯形ABCD中,AD∥BC,AC⊥AB,AD=CD,cos∠DCA=45,BC=10,则AB的值是()A.3B.6C.8D.9
题目详情
如图,在梯形ABCD中,AD ∥ BC,AC⊥AB,AD=CD,cos∠DCA=
|
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
4 |
5 |
A.3 | B.6 | C.8 | D.9 |
▼优质解答
答案和解析
∵在梯形ABCD中,AD ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B. ∵在梯形ABCD中,AD ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B. ∵在梯形ABCD中,AD ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B. ∵在梯形ABCD中,AD ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B. ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B.
4 5 4 4 4 5 5 5 ,AC⊥AB,BC=10,
∴cos∠ACB=
=
=
,
∴AC=8,AB=6.
故选B.
AC BC AC AC AC BC BC BC =
=
,
∴AC=8,AB=6.
故选B.
AC 10 AC AC AC 10 10 10 =
,
∴AC=8,AB=6.
故选B.
4 5 4 4 4 5 5 5 ,
∴AC=8,AB=6.
故选B.
∵在梯形ABCD中,AD ∥ BC,AD=CD, ∴∠DAC=∠DCA=∠ACB. ∵cos∠DCA=
∴cos∠ACB=
∴AC=8,AB=6. 故选B. |
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B. ∥ BC,AD=CD,
∴∠DAC=∠DCA=∠ACB.
∵cos∠DCA=
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
4 |
5 |
∴cos∠ACB=
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
AC |
BC |
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
AC |
10 |
4 |
5 |
∴AC=8,AB=6.
故选B.
4 |
5 |
∴AC=8,AB=6.
故选B.
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