Using properties of determinants, show that ABC is isosceles if `|(1,1,1),(1+cosA,1+cosB,1+cosC),(cos^2A+cosA,cos^2B+cosB,cos^2C+cosC)|=0`

Using properties of determinants, show that triangle ABC is isosceles, if : |(1,1,1),(1+cosA, 1+cosB, 1+cosC),(sqrecosA+cosA, cossqrB+cosB, cossqurC+cosC)| =0

Show that the DeltaABC is an isosceles triangle if the determinant Delta=|{:(1,1,1),(1+cosA,1+cosB,1+cosC),(cos^2A+cosA,cos^2B+cosB,cos^2C+cosC):}|=0

Show that DeltaABC is an isosceles triangle, if the determinant Delta=|(1,1,1),(1+cosA,1+cosB,1+cosC),(cos^(2)A+cosA,cos^(2)B+cosB,cos^(2)C+cosC)|=0 .

Show that DeltaABC is an isosceles triangle, if the determinant Delta=|(1,1,1),(1+cosA,1+cosB,1+cosC),(cos^(2)A+cosA,cos^(2)B+cosB,cos^(2)C+cosC)|=0 .

(a+b+c)(cosA+cosB+cosC)

cos^2 A + cos^2 B +cos^2 C=1+2cosA cosB cosC .

In a A B C ,if|1 1 1 1+cosA 1+cosB 1+cosC cos^2A+A cos^2B+cosB cos^2C+cosC|=0 show that A B C is an isosceles.

In a A B C ,if|1 1 1 1+cosA1+cosB1+cosCcos^2A+cosBcos^2A+cosBcos^2+cosC|=0 show that A B C is an isosceles.

If cosA+cosB+cosC=0, then cos3A+cos3B+cos3C is equal to