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Question

In a triangle, if angle $A = 30^\circ$ and angle $B = 45^\circ$, then what is the angle of C?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
$105^\circ$

Solving for Triangle Angle C

The sum of the interior angles in any triangle is always $180^\circ$. This fundamental property can be represented by the formula:

$ \text{Angle A} + \text{Angle B} + \text{Angle C} = 180^\circ $

Applying the Angle Sum Theorem

We are given the measures of two angles:

  • Angle A = $30^\circ$
  • Angle B = $45^\circ$

Substitute these values into the formula:

$ 30^\circ + 45^\circ + \text{Angle C} = 180^\circ $

Calculating Angle C

First, sum the known angles:

$ 75^\circ + \text{Angle C} = 180^\circ $

Next, isolate Angle C by subtracting $75^\circ$ from both sides:

$ \text{Angle C} = 180^\circ - 75^\circ $

$ \text{Angle C} = 105^\circ $

Therefore, the measure of angle C is $105^\circ$.

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Similar Questions

  1. In $\triangle ABC$, $BD \perp AC$ at $D$ and $\angle DBC = 40^\circ$. $E$ is a point on $BC$ such that $\angle CAE = 37^\circ$. What is the measure of $\angle AEB$?
  2. In $\Delta ABC$, $BD \perp AC$ at D and $\angle DBC = 71^\circ$. E is a point on BC such that $\angle CAE = 17^\circ$. What is the measure of $\angle AEB$?
  3. In triangle ABC, bisector of $\angle\text{ABC}$ and $\angle\text{ACB}$ meet at O. If $\angle\text{BAC} = 60^\circ$, then find the measure of $\angle\text{BOC}$.
  4. In $\Delta\text{XYZ}$, $\text{XY} = 12\text{ cm}$ and $\text{YZ} = 18\text{ cm}$. $\text{XW}$, the angle bisector of $\text{YXZ}$, meets $\text{YZ}$ at $\text{W}$, such that $\text{YW} : \text{WZ}$ is $4 : 5$. Find the length of the third side of the triangle.
  5. In $\Delta\text{PQR}$, $\text{QR}$ is extended up to $\text{S}$ so that $\text{RS} = \text{RP}$. If $\angle\text{PRQ} = 70^\circ$ and $\angle\text{QPS} = 110^\circ$ then find the measure of $\angle\text{PQS}$.
  6. The areas of two similar triangles are respectively $16\text{ m}^{2}$ and $36\text{ m}^{2}$. Find the ratio of their corresponding sides.
  7. In $\Delta PQR$, QR is extended up to S, so that RS = RP. If $\angle RPQ = 55^\circ$ and $\angle PRS = 110^\circ$, then find the measure of $\angle PQS$.
  8. The sides of a triangle are 44 cm, 33 cm, and 55 cm. What is its area? (in $cm^2$)
  9. The perimeter of an equilateral triangle ABC is 22.2 cm. What is the area of triangle (in $cm^2$)?
  10. In $\triangle\text{ABC}$, $\text{BD} \perp \text{AC}$ at $\text{D}$ and $\angle\text{DBC} = 60^{\circ}$. $\text{E}$ is a point on $\text{BC}$ such that $\angle\text{CAE} = 20^{\circ}$. What is the measure of $\angle\text{AEB}$?

Important Questions from Triangles

  1. What is the foot of the altitude from the vertex A of the triangle ABC?

  2. In ΔABC, D is a point on BC such that ∠ADB = 2∠DAC, ∠BAC = 70° and ∠B = 56°. What is the measure of ∠ADC?

  3. In ΔABC, ∠A = 66° and ∠B = 50 °. If the bisectors of ∠B and ∠C meet at P, then ∠BPC – ∠PCA = ?

  4. In a triangle ABC, points P and Q are on AB and AC, respectively, such that AP = 4 cm, PB = 6 cm, AQ = 5 cm and QC = 7.5 cm. If PQ = 6 cm, then find BC (in cm).

  5. The perimeters of two similar ΔABC and  Δ PQR are 48.4 cm and 12.1 cm, respectively. What is the ratio of the areas of  Δ ABC and  Δ PQR?

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