Prove that
(cos x – cos y)2 + (sin x – sin y)2 = 4 sin2
= (cos x – cos y)2 + (sin x – sin y)2
=(-2sin
sin
) 2 +(2cos
sin
) 2
=4 sin2
(sin2
+cos2
)
=4 sin2
Using the formula,
cosA - cosB = -2sin
sin
sinA - sinB = 2cos
sin
1
Prove that
(cos x – cos y)2 + (sin x – sin y)2 = 4 sin2
= (cos x – cos y)2 + (sin x – sin y)2
=(-2sinsin) 2 +(2cossin) 2
=4 sin2(sin2+cos2)
=4 sin2
Using the formula,
cosA - cosB = -2sinsin
sinA - sinB = 2cos sin