Your classmate's error about AB and DC being complimentary and parallel is that they misapplied the alternate angle property.
<h3>Why are AB and DC not parallel?</h3><h3 />
There isn't enough evidence presented in the diagram to say that AB and DC are parallel.
The evidence required would be proof that angle AWZ is equal to angle WZY.
Instead, all we have is that angle AWZ and angle XYC are equal which does not tell us what we need to know about AB and DC being parallel.
Find out more on properties of parallel lines at brainly.com/question/24607467
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Answer:
28
Step-by-step explanation:
His aces on 80 serve = 35% of 80
= 35/100 × 80
= 28
A vector space 
is a subspace of a vector space 
if
- is non-empty,
- for any two vectors
we have 
, and - for any scalar
and 
we have 
.
It's easy to show the first condition is met by all the sets in parts (a-g).
(a) is a subspace of 
because adding any 2x2 diagonal matrices together, or multiplying one by some scalar, gives another diagonal matrix.
(b) and (c) are also subspaces for the same reasons.
(d) is not a subspace because because this set of matrices does not contain the zero matrix.
(e), however, is a subspace. Any linear combination of matrices in this set always yields a matrix with 0 in row 1, column 1 entry.
(f) is a subspace. A symmetric matrix is one of the form
Adding two symmetric matrices gives another symmetric matrix:
(g) is not a subspace. Consider the matrices
Both matrices have determinant 0, but their sum is the identity matrix with determinant 1.
