If sinA=cosA Find the value of (sin4A+cos4A) - Maths - Introduction to Trigonometry

Question

If sinA=cosA Find the value of
(sin4A+cos4A)

Arvind Sundaram · Accepted Answer

SinA = CosA
Cos(90 - A) = CosA
90 - A = A
90 = 2A
A = 45 degrees

Sin4A + Cos4A =
(Sin2A)2 + (Cos2A)2
Sin2 45 = 1/2
Cos2 45 = 1/2
Sin4A + Cos4A = (1/2)2 +
(1/2)2 = 2/4 = 1/2

If sinA=cosA. Find the value of (sin4A+cos4A)