Question

if secA-cosA=2,then sec^4+cos^4=____​

Answer 1

Answer:

secA-cosA=2

squaring both sides

we get

(secA-cosA)² = sec²A + cos²A -2secA.cosA

2² = sec²A + cos²A -2

sec²A + cos²A = 6

squaring both sides

we get

(sec²A + cos²A)² = sec⁴A + cos⁴A +2sec²A.cos²A

6² = sec⁴A + cos⁴A + 2

sec⁴A + cos⁴A = 36-2

sec⁴A + cos⁴A = 34