Define Engel. Engel synonyms, Engel pronunciation, Engel translation, English dictionary definition of Engel. Friedrich 1820-1895. German social theorist who collaborated with Karl Marx on The Communist Manifesto and numerous other works. American Herita
and the curve x_1'u_1+x_2'u_2+x_3'u_3\in T_{\varphi (x_1, x_2, x_3)}M is an integral line of X_g. Under our identification \mathcal {P}C\cong \{{\displaystyle \frac{\cos \theta }{\sqrt{g_{11}}}u_1 + {\displaystyle \frac{\sin \theta }{\sqrt{g_{22}}}...