c) Find \( A \), when \( l=11 \mathrm{~cm} \) and \( r=5.2 \mathrm{~cm} \). 12. A long time ago Dulani found an island shaped like a triangle with three straight shores of length \( 3 \mathrm{~km}, 4 \mathrm{~km} \) and 5 km . He said nobody could come within 1 km of his shore. What was the area of his exclusion zone?

Question 10: A radioactive substance has a half-life of 1620 years. (a) If its mass is now 4 g (grams), how much will be left 810 years from now? (a) Find the time \( t_{1} \) when 1.5 g of the substance remain.

The equation of a curve is \( y=4 x^{2}-12 x+13 \). (a) By expressing \( 4 x^{2}-12 x+13 \) in the form \( a(x-b)^{2}+c \), where \( a, b \) and \( c \) are constants, find the coordinates of the stationary point on the curve.

Шесть эклеров, шоколадное пирожное и два профитроля стоят 850 рублей, а три эклера, два шоколадных пирожных и один профитроль - на 230 рублей дешевле. Сколько стоит набор из трёх эклеров, шоколадного пирожного и профитроля? Ответ выразите в рублях.

2. Kebarangkalian bahawa Sunny menang dalam kuiz Sains dan kuiz Matematik masing-masing ialah \( \frac{1}{3} \) dan \( \frac{1}{7} \). Cari kebarangkalian bahawa dia akan menang dalam kedua-dua kuiz itu. The probability that Sunny wins in the Science quiz and Mathematics quiz are \( \frac{1}{3} \) and \( \frac{1}{7} \) respectively. Find the probability that he will win in both quizzes.

What is the slope of a line that passes through the peints \( (5,3) \) and \( (7,-4) \) ? a.) \( \frac{11}{2} \) b) \( \frac{2}{11} \) c) \( -\frac{7}{2} \) d) \( -\frac{2}{7} \) in