how to plot the graph

PLease tell how to plot the graph from the equation

http://imgur.com/LnfkIJl

Answer 1

[Chandrasekhar]

for i = 1:10 if(t(i) <= 0.75 && t(i) >= 0.5) r(i,1) = (a*(1-cos(8*pi*t)))/2; else r(i,1) = 0; end end

plot(t,r);

[nkumar]

i get error

Undefined function 't' for input arguments of type 'double'.

Error in Untitledgr (line 2) if(t(i) <= 0.75 && t(i) >= 0.5)