`DeltaABC` का परिकेन्द्र O है । यदि `angleBAC=85^(@)` तथा`angleBCA=75^(@)` है, तब `angleOAC` का मान ज्ञात करे?

Options

A. `40^(@)`
B. `60^(@)`
C. `70^(@)`
D. `90^(@)`

Answer

C

Explanation

According to question Given,

`angleABC + angleBCA + angleCAB=180^(@)`
`angleABC=20^(@)`
`therefore angleCOA=2xxangleABC`
`angleCOA=2xx 20=40^(@)`
In `angleAOC`
We know OC=OA
`therefore angleOAC = angleOCA`
`therefore angleOAC + angleOCA + angleCOA = 180^(@)`
`2angleOAC = 180^(@)-40^(@)`
`2angleOAC=140^(@)`
`angleOAC=70^(@)`