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The area of the triangle, formed by the straight lines y=0,12x−5y=0,y = 0, 12x - 5y = 0, and 3x+4y=73x + 4y = 7 is

Solution

✅ Correct Option: 2
  • Line 1: y=0y = 0 (the x-axis)
  • Line 2: 12x−5y=012x - 5y = 0 or y=12x5y = \dfrac{12x}{5}
  • Line 3: 3x+4y=73x + 4y = 7 or y=7−3x4y = \dfrac{7-3x}{4}

Find intersection points:

Point A (lines 1 and 2):

  • When y=0y = 0:

12x=0  ⟹  x=012x = 0 \implies x = 0

So point A is (0,0)(0,0)


Point B (lines 1 and 3):

  • When y=0y = 0:

3x=7  ⟹  x=733x = 7 \implies x = \frac{7}{3}

So point B is (73,0)(\frac{7}{3},0)


  • Point C (lines 2 and 3):

12x5=7−3x4\frac{12x}{5} = \frac{7-3x}{4}

48x5=7−3x\frac{48x}{5} = 7-3x

48x+15x=3548x + 15x = 35

63x=3563x = 35

x=3563=59x = \dfrac{35}{63} = \dfrac{5}{9}

Substitute into line 2:

y=12⋅595=43y = \dfrac{12 \cdot \frac{5}{9}}{5} = \dfrac{4}{3}

So point C is (59,43)(\frac{5}{9}, \frac{4}{3})


Calculate the area using the formula for triangle area given vertices:

Area =12∣x1(y2−y3)+x2(y3−y1)+x3(y1−y2)∣=\dfrac{1}{2}|x_1(y_2-y_3) + x_2(y_3-y_1) + x_3(y_1-y_2)|

=12∣0⋅(0−43)+73⋅43+59⋅0∣=\dfrac{1}{2}|0 \cdot (0-\dfrac{4}{3}) + \dfrac{7}{3} \cdot \dfrac{4}{3} + \dfrac{5}{9} \cdot 0|

=12⋅7⋅43⋅3=\dfrac{1}{2} \cdot \dfrac{7 \cdot 4}{3 \cdot 3}

=12⋅289=\dfrac{1}{2} \cdot \dfrac{28}{9}

=149=\dfrac{14}{9} square units


Alternatively, using Area=12⋅base⋅height\text{Area} = \frac{1}{2} \cdot \text{base} \cdot \text{height}:

Base along x-axis =73=\frac{7}{3}

Height to point C =43=\frac{4}{3}

Area =12⋅73⋅43=149=\dfrac{1}{2} \cdot \dfrac{7}{3} \cdot \dfrac{4}{3} = \dfrac{14}{9} square units

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