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If $l_1 \parallel l_2$, find the sizes of the angles $\alpha$, $\beta$ and $\gamma$ in the following diagram - Junior Cycle Mathematics - Question 11 - 2013

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Question 11

If-$l_1-\parallel-l_2$,-find-the-sizes-of-the-angles-$\alpha$,-$\beta$-and-$\gamma$-in-the-following-diagram-Junior Cycle Mathematics-Question 11-2013.png

If $l_1 \parallel l_2$, find the sizes of the angles $\alpha$, $\beta$ and $\gamma$ in the following diagram. ![Diagram](https://example.com/diagram)

Worked Solution & Example Answer:If $l_1 \parallel l_2$, find the sizes of the angles $\alpha$, $\beta$ and $\gamma$ in the following diagram - Junior Cycle Mathematics - Question 11 - 2013

Step 1

Find $\alpha$

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Answer

We consider the triangle with angles 7373^\circ, 6060^\circ, and 2α2\alpha. The sum of these three angles is 180180^\circ:

2α+73+60=1802\alpha + 73 + 60 = 180

This simplifies to:

2α=1807360=472\alpha = 180 - 73 - 60 = 47

Thus,

α=472=23.5\alpha = \frac{47}{2} = 23.5^\circ

Step 2

Find $\beta$

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Answer

Next, we consider the triangle with angles α\alpha, β\beta, and 7373^\circ. Again, the sum of these angles is 180180^\circ:

73+α+β=18073 + \alpha + \beta = 180

Substituting the value of α\alpha we calculated:

73+23.5+β=18073 + 23.5 + \beta = 180

This simplifies to:

β=1807323.5=83.5\beta = 180 - 73 - 23.5 = 83.5^\circ

Step 3

Find $\gamma$

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101 rated

Answer

Finally, since the two lines are parallel, corresponding angles are equal. Therefore:

γ=α=23.5\gamma = \alpha = 23.5^\circ

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