MCQ
In a $\triangle A B C, B C=A B$ and $\angle B=80^{\circ}$, then $\angle A=$
- A$80^{\circ}$
- B$50^{\circ}$
- C$40^{\circ}$
- D$100^{\circ}$
✓
Answer
B. $50^{\circ}$
We have,
$B C=A B$ and $\angle B=80^{\circ}$$
\begin{array}{ll}
\therefore & \angle A=\angle C \text { and } \angle B=80^{\circ} \\
\text { Now } & \angle A+\angle B+\angle C=180^{\circ} \Rightarrow \angle A+80^{\circ}+\angle A=180^{\circ} \Rightarrow 2 \angle A=100 \Rightarrow \angle A=50^{\circ}
\end{array}
$
We have,
$B C=A B$ and $\angle B=80^{\circ}$$
\begin{array}{ll}
\therefore & \angle A=\angle C \text { and } \angle B=80^{\circ} \\
\text { Now } & \angle A+\angle B+\angle C=180^{\circ} \Rightarrow \angle A+80^{\circ}+\angle A=180^{\circ} \Rightarrow 2 \angle A=100 \Rightarrow \angle A=50^{\circ}
\end{array}
$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
The remainder when $f(x)=x^{45}+x^{25}+x^{14}+x^9+x$ is divided by $g(x)=x^2-1$, is
→Write the correct answer in the following: Angles of a triangle are in the ratio $2 : 4 : 3$. The smallest angle of the triangle is,
→When simplified $(256)^{-\left(4^{-3 / 2}\right)}$, is
→If all the altitudes from the vertices to the opposite sides of a triangle are equal, then the triangle is:
When $p(x) = x^3 - 3x^2 + 4x + 32$ is divided by $(x + a),$ the remainder is:
→Which of the following is a true statement?
In the given figure, $AOB$ is a straight line. If $\angle\text{AOC}=(3\text{x}+10)^\circ$ and $\angle\text{BOC}=(4\text{x}−26)^\circ.$ then $\angle\text{BOC}=?$
→The value of $\sqrt{20} \times\sqrt{5}$ is
→If $\text{x}=\sqrt[3]{2+\sqrt3},$ then $\text{x}^3+\frac{1}{\text{x}^3}=$:
→Write the correct answer in the following:
Euclid stated that all right angles are equal to each other in the form of:
Euclid stated that all right angles are equal to each other in the form of: