化简(1十tan2∝)cos2∝

化简(1十tan2∝)cos2∝
化简(1十tan2∝)cos2∝

化简(1十tan2∝)cos2∝
(1+tan²α)cos²α
=[1 + (sin²α/cos²α)]·cos²α
=[(sin²α+cos²α)/cos²α]·cos²α
=1