How many lines does the diamond have?

Hint: A geometrical shape which has four sides and equal opposite angles is called a diamond. It is a special type of parallelogram which is also known by the name rhombus. The line of symmetry is the imaginary axis passing through the center of the object and divides into two equal halves. Since a diamond has all four sides equal, it has two lines of symmetry.

Complete step-by-step answer:
In this question, we are asked how many lines a diamond has.
Now, diamond is another word used for rhombus. So, a rhombus has 4 sides or we can say that a diamond has 4 sides.
Let us learn more about diamonds or rhombus.
Diamond/rhombus is a parallelogram in which all the sides are of equal length.
Let us see some of the properties of a rhombus/diamond.
 $ \to $ All sides equal.
 $ \to $ Opposite angles equal.
 $ \to $ Diagonals bisect perpendicularly.
 $ \to $ Opposite sides are parallel.
 $ \to $ Sum of two adjacent angles is 180.
 $ \to $ One pair of opposite obtuse angles and one pair of opposite acute angles.
Let us the figure of a diamond.

Hence, we have seen the definition and properties of a diamond/rhombus.

Note: As all the sides of rhombus are equal, its perimeter is given by multiplying the length of its side by 4.
 $ \to $ Perimeter of diamond/ rhombus $ = 4a $ .
And its area can be given by
 $ \to $ Area of diamond/ rhombus $ = \dfrac{1}{2}\left( {{d_1} \times {d_2}} \right) $ .