Qualification > Math

maths c2 edexcel

<< < (2/7) > >>

halosh92:

--- Quote from: astarmathsandphysics on March 11, 2010, 11:26:48 pm ---1)triangle ABC is such that AB=5cm , AC=10 cm and triangle ABC=90 degrees. (angle B=90)
an arc of a circle , center A and radius 5cm cuts AC at D
a) state , in radians the value of angle A in BAC
b)  calculate the are of the region enclosed by BC , DC , and the arc BD
a)pi/3
b)1/2(5*sqrt(75)-5^2)


2) a minor sector OMN of a circle center O and radius "r". the perimeter of the sector is 100cm and the area of the sector is A cm^2
a) show that A=50r-r^2
b) given that r varies , find:
i) the value of "r" for which A is a maximum and show that A is a maximum
ii) the value of MON for this maximum area
iii) the maximum area of sector OMN

a)100=2r+r theta
theta=(100-2r)/r
A=1/2r^2 theta=1/2*r^2*(100-2r)/r=50r-r^2
b)dA/dr=50-2r=0 so r=25
d^2A/dr" =-2<0 hence max
theta=MON=(100-2r)/r=2 when r=25
Area=50r-r^2 =625 when r=25
 

--- End quote ---


for question one, i didnt understand how you got the area of  the region enclosed by BC , DC , and the arc BD

astarmathsandphysics:
When I get up I will draw a diagram

astarmathsandphysics:
here

halosh92:
THX ALOT! ;D

halosh92:
Solve, for 0 ? x < 360, the equation
3 cos2 x° + sin2 x° + 5 sin x° = 0.


how do u come about such questions???????/ step by step explanation plzzzz

Navigation

[0] Message Index

[#] Next page

[*] Previous page