Answer:
Hence, the value of y is:
40
Explanation:
We know that angle opposite to equal sides are equal
In given ΔABC we have:
AB=AC
this means that:
∠B=∠C
Hence,
5x=40
on dividing both side of the equation by 5 we get:
x=8
Hence, we get:
∠B=5x=5×8=40°
i.e. ∠B=40°
Also we know that sum of all the angles of a triangle is 180°.
i.e.
∠A+∠B+∠C=180°
Hence,
2y+20+40+40=180
⇒ 2y+100=180
⇒ 2y=180-100
⇒ 2y=80
On dividing both side of the equation by 2 we obtain:
y=40
Hence, the value of y is:
40