Question

1
2
If a + b2 + c

$a { }^{2} + b {}^{2} + c {}^{2} = 8r {}^{2}$
= 8R2, then prove that the Ale is right angled.
R​

Answer 1

where is the figure which is needed for

Answer 2

Answer:

Answer

a

2

+b

2

+c

2

=8R

2

sin

2

A+sin

2

B+sin

2

C=2

3−(cos2A+cos2B+cos2C)=4

cos2A+cos2B+cos2C=−1

−1−4cosAcosBcosC=−1

cosAcosBcosC=0⟹cosA=0 or cosB=0 or cosC=0

⟹A=90

∘

or B=90

∘

or C=90

∘

⟹ the triangle is right angled