Balbharati Maharashtra State Board11th Commerce Maths Solution Book PdfChapter 5 Locus and Straight Line Miscellaneous Exercise 5 Questions and Answers.
Maharashtra State Board 11th Commerce Maths Solutions Chapter 5 Locus and Straight Line Miscellaneous Exercise 5
(ii) Let C = (1, 3) = (x1, y1) and D = (5, 2) = (x2, y2) say.
Slope of line CD =
(iii) Let E = (-1, 3) = (x1, y1) and F = (3, -1) = (x2, y2) say.
Slope of line EF = = -1
(iv) Let P = (2, -5) = (x1, y1) and Q = (3, -1) = (x2, y2) say.
Slope of line PQ = = = 4
(ii) Given, x-intercept of line is 3 and y-intercept of line is -4
∴ The line intersects X-axis at (3, 0) and Y-axis at (0, -4).
∴ The line passes through (3, 0) = (x1, y1) and (0, -4) = (x2, y2) say.
∴ Slope of line =
(iii) Required line passes through O(0, 0) = (x1, y1) and A(-2, 1) = (x2, y2) say.
Slope of line OA = =
(ii) The points A(1, 3), B(4, 1) and C(3, k) are collinear.
∴ Slope of AB = Slope of BC
∴
∴
∴ 2 = 3k – 3
∴ k =
(iii) Given, point P(1, k) lies on the line joining A(2, 2) and B(3, 3).
∴ Slope of AB = Slope of BP
∴
∴ 1 =
∴ 2 = 3 – k
∴ k = 1
(ii) Equation of a line parallel to Y-axis is x = h.
Since, the line is at a distance of 2 units to the left of Y-axis.
∴ h = -2
∴ the equation of the required line is x = -2
i.e., x + 2 = 0.
(iii) Equation of a line parallel to X-axis with y-intercept ‘k’ is y = k.
Here, y-intercept = 5
∴ the equation of the required line is y = 5.
(iv) Equation of a line parallel to Y-axis with x-intercept ‘h’ is x = h.
Here, x-intercept = 3
∴ the equation of the required line is x = 3.
(ii) Equation of a line perpendicular to Y-axis
i.e., parallel to X-axis, is of the form y = k.
Since, the line passes through (2, 4).
∴ k = 4
∴ the equation of the required line is y = 4.
(iii) Equation of a line perpendicular to X-axis
i.e., parallel to Y-axis, is of the form x = h.
Since, the line passes through (2, 5).
∴ h = 2
∴ the equation of the required line is x = 2.
(ii) Given, slope (m) = 13 and the line passes through (2, 1).
Equation of the line in slope point form is y – y1= m(x – x1)
∴ the equation of the required line is y – 1 = 13(x – 2)
∴ y – 1 = 13x – 26
∴ 13x – y = 25.
(iii) Given, Inclination of line = θ = 90°
∴ the required line is parallel to Y-axis (or lies on the Y-axis.)
Equation of a line parallel to Y-axis is of the form x = h.
Since, the line passes through (7, 3).
∴ h = 7
∴ the equation of the required line is x = 7.
(iv) Given, Inclination of line = θ = 90°
∴ the required line is parallel to Y-axis (or lies on the Y-axis.)
Equation of a line parallel to Y-axis is of the form x = h.
Since, the line passes through origin (0, 0).
∴ h = 0
∴ the equation of the required line is x = 0.
(v) Given equation of the line is 3x + 2y = 2.
∴
∴
This equation is of the form , with
a = , b = 1
∴ the line 3x + 2y = 2 intersects the X-axis at A(, 0) and Y-axis at B(0, 1).
Required line is passing through the midpoint of AB.
∴ Midpoint of AB =
∴ Required line passes through (0, 0) and .
Equation of the line in two point form is
∴ the equation of the required line is
∴ 2y = 3x
∴ 3x – 2y = 0

(ii) Given, Inclination of line = θ = 60°
∴ Slope of the line (m) = tan θ
= tan 60°
= √3
and the y-intercept of the required line is 4.
∴ it passes through (0, 4).
Equation of the line in slope point form is y – y1= m(x – x1)
∴ the equation of the required line is y – 4 = √3(x – 0)
∴ y – 4 = √3x
∴ √3x – y + 4 = 0

(ii) Let D, E, and F be the midpoints of sides BC, AC, and AB respectively of ∆ABC.


(iii) Slope of side BC = = -3
∴ Slope of perpendicular bisector of BC is and the line passes through
∴ Equation of the perpendicular bisector of side BC is
∴
∴ 3(2y – 9) = (2x – 3)
∴ 2x – 6y + 24 = 0
∴ x – 3y + 12 = 0
Since, both the points A and C have the same x co-ordinates i.e. 1
∴ the points A and C lie on the line x = 1.
AC is parallel to Y-axis and therefore, the perpendicular bisector of side AC is parallel to X-axis.
Since, the perpendicular bisector of side AC passes through E(1, 5).
∴ the equation of the perpendicular bisector of side AC is y = 5.
Slope of side AB = = -1
∴ Slope of perpendicular bisector of AB is 1 and the line passes through .
∴ Equation of the perpendicular bisector of side AB is
∴
∴ 2y – 7 = 2x – 3
∴ 2x – 2y + 4 = 0
∴ x – y + 2 = 0
(iv) Let AX, BY and CZ be the altitudes through the vertices A, B, and C respectively of ∆ABC.
Slope of BC = -3
∴ Slope of AX = …..[∵ AX ⊥ BC]
Since, altitude AX passes through (1, 4) and has slope
∴ equation of altitude AX is y – 4 = (x – 1)
∴ 3y – 12 = x – 1
∴ x – 3y + 11 = 0
Since, both the points A and C have the same x co-ordinates i.e. 1
∴ the points A and C lie on the line x = 1.
AC is parallel to Y-axis and therefore, altitude BY is parallel to X-axis.
Since, the altitude BY passes through B(2, 3).
∴ the equation of altitude BY is y = 3.
Also, slope of AB = -1
∴ Slope of CZ = 1 …..[∵ CZ ⊥ AB]
Since, altitude CZ passes through (1, 6) and has slope 1
∴ equation of altitude CZ is y – 6 = 1(x – 1)
∴ y – 6 = x – 1
∴ x – y + 5 = 0
