http://www.ck12.org Chapter 8. Right Triangle Trigonometry
d=√
( 5 − 1 )^2 +( 2 − 5 )^2
=
√
( 4 )^2 +(− 3 )^2
=
√
16 + 9 =
√
25 = 5
Also, just like the lengths of the sides of a triangle, distances are always positive.
Example C
Determine if the following triangles are acute, right or obtuse.
a)
b)
Set the shorter sides in each triangle equal toaandband the longest side equal toc.
a)
62 +( 3√
5 )^2? 8^2
36 +45? 64
81 > 64
The triangle is acute.
b)
152 + 142? 21^2
225 +196? 441
421 < 441The triangle is obtuse.
Watch this video for help with the Examples above.