Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - 9.3 Determinant Solution of Linear Systems - 9.3 Exercises - Page 887: 92

Answer

$${\rm{7 unit}}{{\rm{s}}^2}$$

Work Step by Step

$$\eqalign{ & {\rm{Let\, the\, points\, }}P\left( {\underbrace 2_{{x_1}},\underbrace { - 2}_{{y_1}}} \right),\,\,Q\left( {\underbrace 0_{{x_2}},\underbrace 0_{{y_2}}} \right),\,\,R\left( {\underbrace { - 3}_{{x_3}},\underbrace { - 4}_{{y_3}}} \right) \cr & {\rm{Calcule\, the\, area \,using}} \cr & D = {1 \over 2}\left| {\matrix{ {{x_1}} & {{y_1}} & 1 \cr {{x_2}} & {{y_2}} & 1 \cr {{x_3}} & {{y_3}} & 1 \cr } } \right| \cr & {\rm{Substitute\, the\, values}} \cr & 2D = \left| {\matrix{ 2 & { - 2} & 1 \cr 0 & 0 & 1 \cr { - 3} & { - 4} & 1 \cr } } \right| \cr & {\rm{Calculate\, the\, determinant }} \cr & 2D = 0\left| {\matrix{ { - 2} & 1 \cr { - 4} & 1 \cr } } \right| + 0\left| {\matrix{ 2 & 1 \cr { - 3} & 1 \cr } } \right| + 1\left| {\matrix{ 2 & { - 2} \cr { - 3} & { - 4} \cr } } \right| \cr & 2D = 0 + 0 + \left( { - 8 - 6} \right) \cr & 2D = - 14 \cr & D = - 7 \cr & {\rm{Calculate\, the\, absolute\, value\, of\, }}D \cr & D = 7 \cr & {\rm{The\, area\, of \,the\, triangle\, is \,7 \,unit}}{{\rm{s}}^2} \cr} $$
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