Scientific form = 6.5 x 109.
        
             
        
        
        
Answer:
Interference 
Explanation:
When two traveling waves traveling waves along the same path are superimposed(combine). The superimposition of these two waves results in the production of a resultant wave which is defined by the net effect of the two waves. Wave interference occurs most types of waves including radio wave, light, acoustic waves and other wave types. Alternating sound between loud and Zero is heard as the two speakers emit identical pure tones because the resultant amplitude after the interference of the two sound waves is the vector sum of each of their amplitudes. A loud sound is heard, when the crest of both waves meets each other and a zero is heard if the crest of one meets the trough of the other as they cancel out. 
 
        
             
        
        
        
Answer:
The explorer should travel to reach base camp to 5.02 Km at 4.28° south of due west.
Explanation:
Using trigonometric function like Sen(Ф), Cos(Ф) and Tan(Ф) we can get distance and direction that the explorer should travel to reach base camp. When we discompound the vector  y
 y  so that
 so that  ;
;  to get how far we use Pythagorean theorem so
 to get how far we use Pythagorean theorem so  so that
 so that 
 
        
                    
             
        
        
        
The surrounding environment cool off is the answer