Math Problem Statement

O is the centre of the circle, angle BDA is 25°, angle CAD is 32°, and then angle BOC is

Solution

Based on the provided image and information, you want to find the angle BOCBOC in the circle with OO as its center.

To solve this:

  1. Identify Central and Inscribed Angles:

    • BDA\angle BDA is an inscribed angle that subtends arc BCBC.
    • CAD\angle CAD is also an inscribed angle that subtends arc BDBD.
  2. Relate Inscribed Angles to Central Angles:

    • The central angle BOC\angle BOC subtends the same arc BCBC as the inscribed angle BDA\angle BDA. Recall that a central angle is twice the inscribed angle subtending the same arc.
    • Similarly, BOD\angle BOD is the central angle subtending the arc BDBD, which is twice CAD\angle CAD.
  3. Calculate BOC\angle BOC and BOD\angle BOD:

    • BOC=2×BDA=2×25=50\angle BOC = 2 \times \angle BDA = 2 \times 25^\circ = 50^\circ
    • BOD=2×CAD=2×32=64\angle BOD = 2 \times \angle CAD = 2 \times 32^\circ = 64^\circ
  4. Combine Angles to Find BOC\angle BOC:

    • Since OO is the center, the full angle around point OO is 360360^\circ.
    • If BOC=50\angle BOC = 50^\circ and BOD=64\angle BOD = 64^\circ, then COB\angle COB is part of the remaining circle not covered by these two angles.
  5. Confirm Calculation by Considering Arcs:

    • The arc covered by BOC\angle BOC and BOD\angle BOD together is BC+BDBC + BD. Since BDBD and BCBC collectively cover the circle along with arc CDCD, we should verify the total.
    • BOC+BOD+COD=360\angle BOC + \angle BOD + \angle COD = 360^\circ gives COD=360(50+64)=246\angle COD = 360^\circ - (50^\circ + 64^\circ) = 246^\circ.

Since the text asks specifically for BOC\angle BOC, we conclude it is 5050^\circ.

Would you like further details or have any other questions? Here are some additional topics you might find interesting:

  1. How to calculate the remaining angles in the circle.
  2. The difference between central and inscribed angles.
  3. Applications of circle theorems in real-life situations.
  4. How to construct a circle with given angles using a compass.
  5. The properties of chords and tangents in relation to circle angles.

Tip: Always verify your calculations by ensuring that all angles around a point sum up to 360360^\circ and that all angles in a triangle sum up to 180180^\circ.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Theorems
Angles in Circles

Formulas

Central angle = 2 × Inscribed angle
Sum of angles around a point = 360°

Theorems

Central and Inscribed Angle Theorem
Angle Sum Theorem

Suitable Grade Level

Grades 8-10