Triangle Height Ab
1. **State the problem:** We have a scalene triangle ABC with sides BC = 85.94, AC = 74, and an angle of 45 degrees at vertex B. We want to find the length of side AB and the height from vertex A to base BC.
2. **Identify known values:**
- Side BC = 85.94
- Side AC = 74
- Angle at B = 45 degrees
3. **Use the Law of Cosines to find AB:**
The Law of Cosines states:
$$AB^2 = AC^2 + BC^2 - 2 \times AC \times BC \times \cos(\angle B)$$
Substitute the values:
$$AB^2 = 74^2 + 85.94^2 - 2 \times 74 \times 85.94 \times \cos(45^\circ)$$
Calculate each term:
$$74^2 = 5476$$
$$85.94^2 \approx 7385.2836$$
$$\cos(45^\circ) = \frac{\sqrt{2}}{2} \approx 0.7071$$
Calculate the product:
$$2 \times 74 \times 85.94 \times 0.7071 \approx 2 \times 74 \times 85.94 \times 0.7071 = 2 \times 74 \times 60.75 \approx 2 \times 4495.5 = 8991$$
More precisely:
$$2 \times 74 \times 85.94 \times 0.7071 = 2 \times 74 \times 85.94 \times 0.7071 \approx 8991.1$$
Now compute:
$$AB^2 = 5476 + 7385.2836 - 8991.1 = 12861.2836 - 8991.1 = 3870.1836$$
Take the square root:
$$AB = \sqrt{3870.1836} \approx 62.23$$
4. **Find the height from A to BC:**
The height $h$ can be found using the formula:
$$h = AC \times \sin(\angle B)$$
Since $\sin(45^\circ) = 0.7071$,
$$h = 74 \times 0.7071 \approx 52.13$$
**Final answers:**
- Side AB $\approx 62.23$
- Height from A to BC $\approx 52.13$