Question

tg²α+ctg²α если tgα+ctgα=2

Answer 1

$tg ^{2} +ctg ^{2} =(tg+ctg) ^{2} -2tg*ctg=2^{2} -2=2$
tg*ctg=1
$a^{2} + b^{2} =( a+b)^{2} -2ab$

Answer 2

tga+ctga=2
tg²a+ctg²a=(tga+ctga)²-2tga*ctga=2²-2*1=4-2=2