Answer:
Human system in geography includes settlement , population, literacy, healthcare, technology, trade, tourism, agriculture, production and consumption patterns, waste management etc.
The list is almost endless.
Lava flows are the least hazardous of all processes in volcanic eruptions. How far a lava flow travels depends on the flows temperature, silica content, extrusion rate, and slope of the land. A cold lava flow will not travel far and neither will one that has a high silica content. Such a flow would have a high viscosity<span> (a high resistance to flow). A basalt flow like those in Hawai'i have low silica contents and low viscosities so they can flow long distances. Such a flow can move as far away as 4 km from its source and have a thickness of 10 m (Bryant, 1991). These flows can move at rates of several kilometers per hour (Scott, 1989). </span><span>More silica-rich flows can move as far away as 1.3 km from their sources and have thicknesses of 100 m (Bryant, 1991). These flows can move at rates of a few to hundreds of meters per hour (Scott, 1989). If a lava flow is channelized or travels underground in a lava tube then the distance it travels is greatly extended.</span>
Answer : The value of 
is 
.
Explanation :
As we are given 6 right angled triangle in the given figure.
First we have to calculate the value of 
.
Using Pythagoras theorem in triangle 1 :
Now we have to calculate the value of 
.
Using Pythagoras theorem in triangle 2 :
Now we have to calculate the value of 
.
Using Pythagoras theorem in triangle 3 :
Now we have to calculate the value of 
.
Using Pythagoras theorem in triangle 4 :
Now we have to calculate the value of 
.
Using Pythagoras theorem in triangle 5 :
Now we have to calculate the value of .
Using Pythagoras theorem in triangle 6 :
Therefore, the value of is .
