A right angle always has a measurement of less than 90 degrees. True or false?
2 answers:
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Answer:
Isosceles
Step-by-step explanation:
Consider triangle ABC, BD is the median and the altitude drawn to the side AC. This segment (BD) divide the triangle ABC into two triangles: ABD and CBD.
In these triangles:
- AD=DC (because BD is the median);
- ∠ADB=∠CDB=90° (because BD is the altitude);
- BD is common side.
Thus, by SAS postulate, triangles ABD and CBD are conruent. Congruent triangles have congruent corresponding sides. Hence, AB=CB.
If in triangle ABC, AB=BC, then this triangle is isosceles.
