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AB = 6 cm, AC = 12 cm, CD = ?
In triangle ABC, ∠CBA = 90°, therefore in triangle BCD ∠CBD = 90° also.
Since ∠BDC = 55°, ∠CBD = 90°, and there are 180 degrees in a triangle, we know ∠DCB = 180 - 55 - 90 = 35°
In order to find ∠BCA, use the law of sines:
sin(∠BCA)/BA = sin(∠CBA)/CA
sin(∠BCA)/6 cm = sin(90)/12 cm
sin(∠BCA) = 6*(1)/12 = 0.5
∠BCA = arcsin(0.5) = 30° or 150°
We know the sum of all angles in a triangle must be 180°, so we choose the value 30° for ∠BCA
Now add ∠BCA (30°) to ∠DCB = 35° to find ∠DCA.
∠DCA = 30 + 35 = 65°
Since triangle DCA has 180°, we know ∠CAD = 180 - ∠DCA - ∠ADC = 180 - 65 - 55 = 60°
In triangle DCA we now have all three angles and one side, so we can use the law of sines to find the length of DC.
12cm/sin(∠ADC) = DC/sin(∠DCA)
12cm/sin(55°) = DC/sin(60°)
DC = 12cm*sin(60°)/sin(55°)
DC = 12.686 cm
Answer/Step-by-step explanation:
✔️As a set of order pairs, the mapping can be represented as (x, y), where x = input and y = output.
Thus:
{(1, 6), (2, 6), (3, 6), (4, 8)}
✔️As a table we have input as x, and y as output, such as:
x | y
1 | 6
2 | 6
3 | 6
4 | 8
Answer: Choice A. sin(A) = cos(B)
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Explanation:
The rule is that sin(A) = cos(B) if and only if A+B = 90.
Note how
- sin(A) = opposite/hypotenuse = BC/AB
- cos(B) = adjacent/hypotenuse = BC/AB
Since both result in the same fraction BC/AB, this helps us see why sin(A) = cos(B). Similarly, we can find that cos(A) = sin(B).
In the diagram below, the angles A and B are complementary, meaning they add to 90 degrees. So this trick only applies to right triangles.
The side lengths can be anything you want, as long as you're dealing with a right triangle.
3(x+5)=39
3 * x + 3 * 5 = 39
3x + 15 = 39
3x = 39 - 15
3x= 24
x = 8
