To find the intersection of this line with the earth, plug the line equations into formula_64, to get formula_231, where formula_232 = formula_233,  formula_234 = formula_235, formula_236 = formula_237. Therefore, the line intersects the earth at formula_238. If formula_239, then there is no intersection. If formula_240, then the line is tangent to the earth at formula_241 (i.e. the sections intersect at that single point). Observe that formula_242 since formula_151 and formula_154are not colinear. Plugging t into formula_43 = formula_13 + tformula_162, gives the points of intersection of the earth sections.  on an earth section path may be found by dropping the subscripts on the given section; formula_248, formula_249, and setting formula_250, so that formula_251. Then solve for formula_252 such that formula_240. Since formula_254, and formula_255, we must have formula_256. Plugging t into formula_43 = formula_258, gives the points of intersection of the earth sections. Alternatively, just set formula_259.  on an earth section path may be found by dropping the subscripts on the given section; formula_248, formula_249, and setting formula_262, where formula_263 is the longitude to be solved for such that formula_240. Alternatively, just set formula_265. Operation Penada  Operation Penada was the name of a Portuguese military operation that occurred during the Portuguese Colonial War in Mozambique, in April 1972. The Portuguese 31st Battalion of Hunters took part in the operation, the battalion had been stationed in Furancungo. The inability of Portuguese forces to control the entry of FRELIMO guerrillas into the surrounding territory of the Cahora Bassa dam, who came via Zambia or Rhodesia, led to increasing pressure on the Portuguese from the Rhodesian Security Forces, who criticised the apathy and lack of information about the enemy's movement. The 31st Parachute Hunters Battalion was launched along the borders of those two countries to counter the incursions by guerrillas. The battalion was supported by air support by helicopters. Elements of the Rhodesian Security Forces penetrated Mozambique, pursuing guerrillas, while full units were involved in military operations with Portuguese forces, notably by helicopter detachments stationed at Chicoa and Pisteiros.