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Applications
1. A small electric component is in the shape of a triangle
with sides 6.23, 8.146 and 11.392 millimeter. Find the largest angle.
Solution
Let a = 6.23, b = 8.146 and c = 11.392
Angle opposite to the largest side is the largest angle.
\ cos C = a2 + b2 - c2
= (6.23)2 + (8.146)2 -(11.392)2 = -0.242
2. A car moves from place A to place B,
AB = 2 km. Then it moves to place C. BC = 3 km. Finally it returns
to A. CA =Ö7 km. Find the greatest
angle through which the car had taken a turn and also show that
the triangular course represents an acute angled triangle.
Solution
AB = 2 , BC = 3, CA = Ö 7
i.e. c = 2 , a = 3 and b = Ö 7
Since a = 3 is the greatest side,
the angle A opposite to it is the greatest.
Also angle A is the greatest, therefore triangle
ABC is acute angled triangle.
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