In Δ RST (See Fig. 9.51), what is value of x ?
In
∠ROT + ∠RTO + ∠TRO = 180o
140o+ b + a = 180o
a + b = 40o (i)
∠RST + ∠SRT + ∠STR = 180o
x + a + a + b + b = 180o
x + 2 (a + b) = 180o
x + 80o = 180o
x = 100o