Select all the statements that must be true. (Lesson \( 2-13 \) ) \( \begin{array}{ll}\square & \text { A) Parallelograms have four congruent sides. } \\ \square & \text { B) Both sets of opposite sides of a parallelogram are parallel and congruent. } \\ \square & \text { C) A trapezoid is a parallelogram. } \\ \square & \text { D) Diagonals of a parallelogram bisect each other. } \\ \square & \text { E) Diagonals of a parallelogram are congruent. }\end{array} \)

Find the area of the sector of a at the centre is \( 140^{\circ} \). (Take \( \pi= \) Solution Area A of a sector is given by; \( \begin{aligned} \text { A }=\frac{\theta}{360} \times \pi r^{2}\end{aligned} \) \( \begin{aligned} \therefore \text { Area } & =\frac{140}{360} \times \frac{22}{7} \times 3^{2} \\ & =11 \mathrm{~cm}^{2}\end{aligned} \)

\( =11 \mathrm{~cm}^{2} \) Example 2 The area of a sector of a circle is 38.5 cm if the angle subtended at the centre is 90

A tree is broken at a height of 5 m from the ground and its top touches the ground at a distance of 12 m from the base of the tree. Find the original height of the tree.

3 треугольнике \( A B C \) к стороне \( A B=9 \) см опущена высота, длина которой составила 8 см Найди площадь этого треугольника и дай ответ з квадратных сантиметрах.

4. Which of the following can be the sides of a right triangle? (i) \( 2.5 \mathrm{~cm}, 6.5 \mathrm{~cm}, 6 \mathrm{~cm} \). (iii) \( 2 \mathrm{~cm}, 2 \mathrm{~cm}, 5 \mathrm{~cm} \). (iii) \( 1.5 \mathrm{~cm}, 2 \mathrm{~cm}, 2.5 \mathrm{~cm} \).