A cone height is 9cm has a volume of n cm3 and a curved surface area of ncm2. Find the vertical angle of the cone
The answer in my text book is 38.9degrees
h=9cm, v=n cm^3, c.s.a=n cm^2. Volume of cone is 1/3*22/7*r^2*h, therefore n=1/3*22/7*r^2*9=66r^2/7 therefore n=66r^2/7 now cross multiply 7n=66r^2 b.b.s by 66 we get r^2=7n/66 therefore r=√7n divided by √66. Also c.s.a=πrl therefore n=22/7*√7n divided by √66*l.then we have 22l*√7n* √66*7=n. Cross multiply, we have 22l *√7n=n*7√66 d. b.s by 22√7n=7n√66/22√7n.
When you have a cone, in order to find vertical angle, divide the cone into two. We then have two right angled triangles. Let the missing angle be represented with @. Now using sin@=r/l. There4 sin@=√7n/√66÷7n√66/22√7n=√7n/√66*22√7n/7n√66=154n÷7n*66=154n*1/7n*66=22/66. Therefore sin@=22/66= 0.333. Therefore sin@=0.333.@=sin–¹0.333=19.45.vertical angle=2@=2*19.45=38.9
I checked the answers in my textbook and I got to know that the answer to this question was 38.9 degree instead of the answer chrome gave me
That is what they wrote in my textbook 38.9°
Pls help me to solve it now
Thanks you saved me from Mr isa
Too complicated
What question
I do get it
The person that solved it should snap it so as to make it more understandable