How do I prove that -LRB- -LRB- sinA -RRB- ^ 2 -RRB- +1 / -LRB- sinA -RRB- ^ 2 -RRB- -LRB- -LRB- cosA -RRB- ^ 2 -RRB- +1 / -LRB- cosA -RRB- ^ 2 -RRB- -RRB- ≥ 25/4 ?
How do I prove that 1 + sinA-cosA/1 + sinA + cosA = sinA/2 ?