Answer:
See explanation below
Step-by-step explanation:
BD - diagonal Added Construction
m∠CBD = m∠ADB Alternate Interior Angles Theorem
BD ≅ DB Reflexive Property
m∠A = m∠C Opposite ∠'s Congruent Theorem
ΔABD ≅ ΔCDB AAS or SAS
BC ≅ DA CPCTC
AC - diagonal Added Construction
m∠BCA = m∠CAD Alternate Interior Angles Theorem
AC ≅ CA Reflexive Property
m∠B = m∠D Opposite ∠'s Congruent Theorem
ΔABC ≅ ΔCDA AAS or SAS
AB ≅ CD CPCTC
Answer:
Letters can be chosen in 12 different ways, if order matters, or 6 different ways, if order doesn't matter.
Step-by-step explanation:
Since we want to choose 2 letters, without replacement, from the 4 letters A, B, C, and D, to determine in how many ways can this be done, if the order of the choices matters, and in how many ways can this be done, if the order of the choices does not matter, the following calculations must be performed:
If order matters =
(4 x 3 x 2 x 1) / 2 = X
24/2 = X
12 = X
If the order doesn't matter =
12/2 = X
6 = X
Therefore, letters can be chosen in 12 different ways, if order matters, or 6 different ways, if order doesn't matter.
You multiply straight across, and one number is a fraction and the other is not.
