Need a Hand (2 Viewers)

[Mc_Meaney]

Q1 Find the exact area of the minor segment if
a) Radius is 3m and angle is pi/3

b) Radius is 10cm and angle is 5pi/6

 

[pLuvia]

Area of a segment
1/2r²(θ-sinθ), θ is in radians
a)
A=1/2(3)²(pi/3-sin{pi/3})
A=0.8153m²
b)
A=1/2(10)²(5pi/6-sin{5pi/6})
A=166.435m²

 

[Mc_Meaney]

Can someone help me make sense out of this question:

"Given the wingspan of an aeroplane is 30m, find the plane's altitude to the nearest metre if the wingspan subtends an angle of 14' when directly overhead

 

[SoulSearcher]

Its asking you to find the straight line distance from the observer to the plan. Since the edges of the wings make an angle of 14' with the observer, draw a triangle joining the edges of the wing to the observer. then solve from there by drawing a perpendicular line to the wing from the observer, then use trig ratios.

 

[Mc_Meaney]

Edit: Helps if you use the right ratio lol =] Thanks 4 ur help

 

[Mc_Meaney]

Just one more question

f(x)e^2x(1-x)

Oops product rule. Should be

-3-2x/e^2x

Is that better?

 

[SoulSearcher]

What is the question?

 

[Mc_Meaney]

OOps! Sorry

Differentiate F(x)

then need to find the stationary point on that curve.

By my reconing its like...(-1.5,0.124) but I dont if its right.

 

[SoulSearcher]

Ok then, f(x) = e^2x(1-x)
f'(x) = 2e^2x(1-x) - e^2x
= e^2x(1-2x)
f'(x) = 0 to find stationary points
0 = e^2x(1-2x), but as e^2x cannot equal 0, then
1-2x = 0
2x = 1
x = 1/2
therefore f(1/2) = e^2*0.5 * (1-0.5)
= 0.5e,
therefore coordinate of stationary point is (0.5, 0.5e)

 

[KnightSaber]

Can someone help me make sense out of this question:

"Given the wingspan of an aeroplane is 30m, find the plane's altitude to the nearest metre if the wingspan subtends an angle of 14' when directly overhead

tan14 = x/30

x= 7.4798m '''



Lol i hope the plane isnt acutally flying...

when u say over head do u mean the person is standing underneath the plane?

Please use angles of D & A

 

[Riviet]

Agreed with webby.

 

[Riviet]

The distance between the tips of the wings, as of a bird or insect, when fully extended.

Ah yes, understanding exactly what the question is asking is always important.

 

[SoulSearcher]

I should have posted the diagram up then, but this'll do.

 

[Mc_Meaney]

FInd y' if:

y= (cosx)^-1

Help please

Thanx

 

[insert-username]

I assume this is cos x all to the power of -1. You use the chain rule:

dy/dx = dy/du . du/dx where u = cos x

dy/dx = -(cosx)^-2.(-sinx)

= sinx/cos²x

= tan x sec x


I_F

 

[Mc_Meaney]

thankya