http://www.ck12.org Chapter 8. Right Triangle Trigonometry
AB=
√
(− 4 − 3 )^2 +( 1 − 8 )^2 =
√
49 + 49 =
√
98 = 7
√
2
BC=
√
( 3 − 9 )^2 +( 8 − 6 )^2 =
√
36 + 4 =
√
40 = 2
√
10
AC=
√
(− 4 − 9 )^2 +( 1 − 6 )^2 =
√
169 + 25 =
√
194
Now, let’s plug these lengths into the Pythagorean Theorem.
(√
98
) 2
+
(√
40
) 2
?
(√
194
) 2
98 +40? 194
138 < 194
4 ABCis an obtuse triangle.
- Acute because 7^2 + 82 > 92.
- Right because 14^2 + 482 = 502
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Find the area of each triangle below. Round your answers to the nearest tenth.