Q) If sin θ – cos θ = 0, then find the value of sin4 θ + cos4 θ.
Ans: Since sin θ – cos θ = 0
sin θ = cos θ
hence tan θ = 1 and θ = 450
and hence sin 450 = cos 450 = 
sin4 θ + cos4 θ
= sin4 45 + cos4 45
= 
+
= 
+
= 
Skip to contentQ) If sin θ – cos θ = 0, then find the value of sin4 θ + cos4 θ.
Ans: Since sin θ – cos θ = 0
sin θ = cos θ
hence tan θ = 1 and θ = 450
and hence sin 450 = cos 450 =
sin4 θ + cos4 θ
= sin4 45 + cos4 45
= +
= +
=