1+ катангенс квадрат альфа= 1/синус квадрат альфа.
а тангенс находи через катангенс
{√(x²-7)>3⇒x²-7>9⇒(x²-16)>0⇒(x-4)(x+4)>0⇒x<-4 U x>4
{|2-3x|≤13⇒-13≤2-3x≤13⇒-15≤-3x≤11⇒-3 2/3≤x≤5
\\\\\\\\\\\\\\ /////////////////////////////////
----------(-4)-------[3 2/3]-------------(4)---------[5]------------
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x∈(4;5]
A) 10a^2 - 6ab + b^2;
b) 9b^2 - a^2 +6ab - 9b^2 = 6ab - a^2;
c) 25a^2+70ab +49b^2 - 70ab = 25a^2 + 49b^2;
d) 64a^2 - 16ab +b^2 - 64a^2 = b^2 - 16ab