Math Problem Statement

In this triangle (not drawn to scale) the angle at A is twice that at B, while the angle at B is 16° more than that at C. What is the value of the angle at A ?

Solution

Let's call the angles at vertices AA, BB, and CC as A\angle A, B\angle B, and C\angle C, respectively.

Step 1: Express relations between the angles.

From the problem:

  • A=2×B\angle A = 2 \times \angle B (Angle at AA is twice that of BB).
  • B=C+16\angle B = \angle C + 16^\circ (Angle at BB is 16° more than that at CC).

Step 2: Set up the equation for the sum of the angles.

In any triangle, the sum of the interior angles is always 180180^\circ: A+B+C=180\angle A + \angle B + \angle C = 180^\circ

Step 3: Substitute the relations into the sum equation.

We already have A=2×B\angle A = 2 \times \angle B and B=C+16\angle B = \angle C + 16^\circ. We can substitute C\angle C as B16\angle B - 16^\circ into the equation.

Now, substituting into the sum of angles: 2×B+B+(B16)=1802 \times \angle B + \angle B + (\angle B - 16^\circ) = 180^\circ

Step 4: Simplify the equation.

2B+B+B16=1802\angle B + \angle B + \angle B - 16^\circ = 180^\circ 4B16=1804\angle B - 16^\circ = 180^\circ 4B=1964\angle B = 196^\circ B=1964=49\angle B = \frac{196^\circ}{4} = 49^\circ

Step 5: Calculate A\angle A.

Now that we know B=49\angle B = 49^\circ, we can calculate A\angle A: A=2×B=2×49=98\angle A = 2 \times \angle B = 2 \times 49^\circ = 98^\circ

Step 6: Calculate C\angle C.

Using B=C+16\angle B = \angle C + 16^\circ, we find: C=B16=4916=33\angle C = \angle B - 16^\circ = 49^\circ - 16^\circ = 33^\circ

Thus, the angles in the triangle are:

  • A=98\angle A = 98^\circ
  • B=49\angle B = 49^\circ
  • C=33\angle C = 33^\circ

The value of A\angle A is 98°.

Would you like further details or have any questions?

Here are five related questions:

  1. How do you solve for the angles of an isosceles triangle?
  2. What is the sum of the interior angles in a quadrilateral?
  3. Can you prove why the sum of angles in any triangle is 180°?
  4. How does the exterior angle theorem apply in triangles?
  5. What is the difference between an acute and obtuse triangle?

Tip: Remember, the sum of the interior angles of any polygon is (n2)×180(n - 2) \times 180^\circ, where nn is the number of sides.

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangle Angles
Linear Equations

Formulas

Sum of angles in a triangle: A + B + C = 180°
Angle A = 2 * Angle B
Angle B = Angle C + 16°

Theorems

Triangle Angle Sum Theorem

Suitable Grade Level

Grades 6-8