Question

In triangle ABC, the size of angle B is 4 times the size of angle A, and the size of angle C is 6°

less than 5 times the size of angle A.
Find the size of the angles.

Answer 1

<A = 18.6 Degree

<B =74.4 Degree

<C = 87 Degree

Explanation:

Sum of all the angles of triangle is 180

as given ,

<A = ?

<B = 4<A

<C = 5 <A - 6

As per rule ,

<A + <B +<C = 180

<A + 4 <A + 5<A - 6 = 180

10 <A - 6 = 180

10 <A = 180 + 6

<A = 186 / 10

<A = 18.6 Degree

Hence ,

< B = 4 X (18.6)

< B = 74.4 Degree

and

<C = 5 (18.6) - 6

<C = 87 Degree

PROOF

<A + <B + <C = 180

18.6 + 74.4 + 87 = 180

180 = 180