ABC Right triangle
If
Calculate the size of
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ABC Right triangle
If
Calculate the size of
Note that angle BDA equals 90 degrees, therefore we can deduce that angle BDC also equals 90 degrees.
Let's look at triangle ABC and calculate angle C, since angles A and B are given to us:
Now let's focus on triangle BDC and calculate angle alpha, since we have calculated the other two angles.
30
Indicates which angle is greater
Point D lies on the altitude from B to side AC. By definition, an altitude is perpendicular to the opposite side, which means it forms 90° angles with that side.
Since BD is perpendicular to AC at point D, it creates two right angles: angle BDA and angle BDC. Both angles are on a straight line AC, so each must be 90°.
To solve triangle BDC, you need all three angles. You know angle BDC = 90°, so finding angle ACB (which equals 60°) gives you two angles to find the third.
No! You need angle ACB from triangle ABC to complete the calculation in triangle BDC. The triangles are connected - they share angle C.
Double-check your work: In right triangle ABC, . So , giving ∠C = 60°.
Check triangle BDC: ✓. The angles sum correctly!
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