EFFECT : I need help with this one. CAUSE : Zheng He's expeditions along the coasts of Southeast Asia and India found entrances to the Red Sea and Persian Gulf.​

Find the value of the cosine for angle a

If there are 12 moths and some have 31 days and others have 30 days how many have 28 days?

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?