Răspunsuri

2014-03-20T22:41:08+02:00
\dfrac{1}{cos^215^{\circ}}+\dfrac{1}{sin^215^{\circ}}=\dfrac{sin^215+cos^215}{sin^215cos^215}=\dfrac{1}{(sin15cos15)^2}=

=\dfrac{4}{(2sin15cos15)^2}= \dfrac{4}{sin^230}=\dfrac{4}{\dfrac14}=16.

Am folosit formula fundamentala a trigonometriei>

sin^2x+cos^2x=1, \forall x
Am folosit si formula 2sinx\cdot cosx=sin2x

am completat la raspuns.
multumesc
insa tot nu inteleg ce ai facut mai departe
am mai completat
multumesc!