J's answer to Tammy Chan's Hong Kong question.
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c)
This one is easy. We just need the base and height of the triangle.
For the base, we can use the length of OQ. Since OQ is on the y-axis, it is a vertical line.
The length of OQ is simply the absolute difference of the y-coordinates of the origin O (coordinates(0,0)) and Q.
Length of OQ = (0 - (-7)) units = (0 + 7) units = 7 units
For the height, we'll use the length of the perpendicular from P to the y-axis.
Now P has the coordinates (4,9). The 4 means that it is 4 units horizontally right of the y-axis. The 9 means that it is 9 units vertically/directly above the x-axis.
This means that the length of the perpendicular is 4 units, since the perpendicular is effectively the same as this horizontal distance.
So the triangle has height of 4 units, base of 7 units.
Area of triangle = ½ × base × height = ½ × 7 units × 4 units
= 14 units ²
This one is easy. We just need the base and height of the triangle.
For the base, we can use the length of OQ. Since OQ is on the y-axis, it is a vertical line.
The length of OQ is simply the absolute difference of the y-coordinates of the origin O (coordinates(0,0)) and Q.
Length of OQ = (0 - (-7)) units = (0 + 7) units = 7 units
For the height, we'll use the length of the perpendicular from P to the y-axis.
Now P has the coordinates (4,9). The 4 means that it is 4 units horizontally right of the y-axis. The 9 means that it is 9 units vertically/directly above the x-axis.
This means that the length of the perpendicular is 4 units, since the perpendicular is effectively the same as this horizontal distance.
So the triangle has height of 4 units, base of 7 units.
Area of triangle = ½ × base × height = ½ × 7 units × 4 units
= 14 units ²
Date Posted:
3 years ago