Mathematics
Study the graph and answer the following questions :
(a) Write down the co-ordinates of points A, B and C.
(b) Calculate the area of triangle ABC.
Reflection
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Answer
(0, 4), (-5, -2) and (5, -2); 30 sq. units
Reason
(a) From graph,
Coordinates of A = (0, 4), B = (-5, -2) and C = (5, -2).
(b) From graph,
1 block = 1 unit and AD is the height of triangle ABC.
BC = 10 units
AD = 6 units
We know that,
Area of triangle =
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Related Questions
Study the graph and answer each of the following :
(a) Write the coordinates of points A, B, C and D.
(b) Given that, point C is the image of point A. Name and write the equation of the line of reflection.
(c) Write the coordinates of the image of the point D under reflection in y-axis.
(d) What is the name given to a point whose image is the point itself ?
(e) On joining the points A, B, C, D and A in order, a figure is formed. Name the closed figure.
Assertion (A) : The point (-2, 8) is invariant under reflection in line x = -2
Reason (R) : If a point has its x-coordinate 0, it is invariant under reflection in both axes.
Both A and R are correct, and R is the correct explanation for A.
Both A and R are correct, and R is not the correct explanation for A.
A is true, but R is false.
Both A and R are true.
(a) Point P(2, -3) on reflection becomes P'(2, 3). Name the line of reflection (say L1).
(b) Point P' is reflected to P'' along the line (𝐿2), which is perpendicular to the line 𝐿1 and passes through the point, which is invariant along both axes. Write the coordinates of P''.
(c) Name and write the coordinates of the point of intersection of the lines 𝐿1 and 𝐿2.
(d) Point P is reflected to P''' on reflection through the point named in the answer of part I of this question. Write the coordinates of P'''. Comment on the location of the points P'' and P'''.
Use graph paper for this question :
Use 1 cm = 1 unit on both the axes.
(i) Plot the points A(4, 5) and B(-1, -3)
(ii) A' is the image of A when reflected in the y-axis. Write down the co-ordinates of A' and plot it on the graph paper.
(iii) B' is the image of B when reflected in the x-axis followed by reflection in the origin. Write down the co-ordinates of B' and plot it on the graph paper.
(iv) Write down the geometrical name of the figure AA'BB'.
(v) Name two invariant points under reflection in y-axis.