a)
[tex] \alpha = {180}^{o} - {53}^{o} - {40}^{o} \\ \alpha = {87}^{o} [/tex]
b)
[tex] \beta = {180}^{o} - {60}^{o} - {55}^{o} \\ \beta = {65}^{o} [/tex]
c)
[tex] \gamma = {180}^{o} - {90}^{o} - {35}^{o} \\ \gamma = {55}^{o} [/tex]
d)
[tex] \delta = {180}^{o} - {90}^{o} - {57}^{o} \\ \delta = {33}^{o} [/tex]
