Explications étape par étape:
a. sin83° = 2,1/ET
ET *sin83° = 2,1
ET = 2,1/sin83°
b. cos P = SP/RP
cos 19° = 5/RP
RP * cos 19° = 5
RP = 5/cos19
RP = environ 5,3 cm
c. tan P = RS/SP
tan19° = RS/5
5 * tan19° = RS
Donc RS =environ 1,72cm