How Do You Calculate the Radius and Surface Area of a Cone Formed from a Sector?

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SUMMARY

The discussion focuses on calculating the radius and surface area of a cone formed from a circular sector with a radius of 8 cm and a central angle of 3π/4 radians. It is established that the base of the cone has a radius of 3 cm. Additionally, the discussion includes a problem involving a plane's altitude and distance traveled, leading to the formula for altitude: h = 10000sin50 tan25/sin65. The angle of elevation from the observation point is also calculated.

PREREQUISITES
  • Understanding of circular sectors and cones
  • Knowledge of trigonometric functions and their applications
  • Familiarity with radians and degrees
  • Ability to perform calculations involving angles of elevation
NEXT STEPS
  • Study the derivation of the formula for the radius of a cone from a sector
  • Learn about the relationship between angles in trigonometry
  • Explore the concept of angle of elevation and its applications in real-world scenarios
  • Investigate the properties of cones and their surface area calculations
USEFUL FOR

Students studying geometry, mathematics educators, and anyone interested in applying trigonometry to real-world problems involving angles and distances.

kr73114
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1) A piece of paper is in the shape of a sector of a circle. The radius is 8cm and the angle at the centre is 3pi/4 radians. The straight edges of the sector are placed together so that a cone is formed. Show that the base of the cone has a radius of 3cm. Find the area of theh curved surface of the cone.

2) A plane flying due east at 600km/h at a constant altitude. From an observation point P on the ground the plane is sighted on a bearing of 320o. One minute later the bearing of the plane is 75o and its angle of elevation is 25o. How far has the plane traveled between sightings. Draw a diagram to represent the information given. Show that the altitude h metres of the plane is given by
h= 10000sin50 tan25/sin65 and hence find h. Find correct to the nearest degree the angle of elevation of the plane from P when first sighted.
 
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welcome to pf!

hi kr73114! welcome to pf! :smile:

(have a pi: π and a degree: ° :wink:)

show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
 

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