- A
- B
- C
- D
Step-by-Step Solution
For an obtuse triangle the height can lie outside. Area .
Answer: C)
In triangle ABC, the base BC is 6 cm. The height AD falls outside the triangle, on BC extended (dashed). Find the area of triangle ABC.
Class 7Perimeter and AreaPerimeter and Area
Key idea: Triangle area
**Area of a triangle = ½ × base × height.**
The base is any side you choose; the height is the perpendicular distance from that base to the opposite vertex (NOT the slant length of another side). For a right triangle, the two legs that meet at the right angle ARE the base and height.
Example: triangle with base 6 cm and height 4 cm. Area = ½ × .
The perimeter of a triangle is just the sum of its three sides — no formula needed.
The base is any side you choose; the height is the perpendicular distance from that base to the opposite vertex (NOT the slant length of another side). For a right triangle, the two legs that meet at the right angle ARE the base and height.
Example: triangle with base 6 cm and height 4 cm. Area = ½ × .
The perimeter of a triangle is just the sum of its three sides — no formula needed.
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