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3 and 4 .Determinants and Matrices
easy
एक त्रिभुज का क्षेत्रफल ज्ञात कीजिए जिसके शीर्ष $(3,8),(-4,2)$ और $(5,1)$ हैं।
A
$\frac {61}{2}$
B
$\frac {65}{2}$
C
$\frac {71}{2}$
D
$\frac {33}{2}$
Solution
The area of triangle is given by
$\Delta = \frac{1}{2}\left| {\begin{array}{*{20}{r}}
3&8&1 \\
{ – 4}&2&1 \\
5&1&1
\end{array}} \right|$
$ = \frac{1}{2}[3(2 – 1) – 8( – 4 – 5) + 1( – 4 – 10)]$
$ = \frac{1}{2}(3 + 72 – 14) = \frac{{61}}{2}$
Standard 12
Mathematics